bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust Multi-Objective Control of Power System Stabilizer Using Mixed H2/H∞ and µ Analysis
Authors: Fard Javad Mashayekhi
Published: January 2019

In order to study the dynamic stability of the system, having a precise dynamic model including the energy generation units such as generators, excitation system and turbine is necessary. The aim of this paper is to design a power stabilizer for Mashhad power plant and assess its effects on the electromechanical fluctuations. Due to lack of certainty in the system, designing an optimized robust controller is crucial. In this paper, the establishment of balance between the nominal and robust performance is done by the weight functions. In the frequencies where the uncertainty is high, in order to achieve to the robust performance of the controller, μ analysis is more profound, otherwise, in order to achieve to nominal performance, robust stability, noise reduction and decrease of controlling signal, the impact of the controller H2/H∞ is more profound. The results of the simulation studies represent the advantages and effectiveness of the suggested method.
Performance Investigation of Grid Connected Photovoltaic System Modelling Based on MATLAB Simulation
Authors: Ali Adnan Hussein , Hamad Hassan Salman , Abdulrazzaq Ali Abdulwahhab
Published: January 2019

Photovoltaic (PV) systems are normally modeled by employing accurate equations dealing with a behavior the PV system. This model has Characteristic of PV array cells, which are influenced by both irradiation and temperature variations. Grid-connected PV system is considered as electricity generated solar cell system which is connected to the grid utilities. This paper characterizes an exhibiting and simulating of PV system that executed with MATLAB /Simulink. The impact of solar irradiances as well as ambient temperature performances of PV models is investigated and noted that a lower temperature provides maximum power higher so that the open circuit voltage is larger. Furthermore, if the temperature is low, then a considerably short circuit current is low too.
Revealing AES Encryption Device Key on 328P Microcontrollers with Differential Power Analysis
Authors: Putra Septafiansyah Dwi , Ahmad Adang Suwandi , Sutikno Sarwono , Kurniawan Yusuf , Sumari Arwin Datumaya Wahyudi
Published: January 2019

This research demonstrates the revealing of an advanced encryption standard (AES) encryption device key. The encryption device is applied to an ATMEGA328P microcontroller. The said microcontroller is a device commonly used in internet of things (IoT). We measured power consumption when the encryption process is taking place. The message sent to the encryption device is randomly generated, but the key used has a fixed value. The novelty of this research is the creation of a systematic and optimal circuit in carrying the differential power analysis or difference of means (DPA/DoM) technique, so the technique can be applied in key revealing on a microcontroller device by using 500 traces in 120 seconds.
Improving IF Algorithm for Data Aggregation Techniques in Wireless Sensor Networks
Authors: Ingle Madhav , Rao PVRD Prasada
Published: January 2019

In Wireless Sensor Network (WSN), fact from different sensor nodes is collected at assembling node, which is typically complete via modest procedures such as averaging as inadequate computational power and energy resources. Though such collections is identified to be extremely susceptible to node compromising attacks. These approaches are extremely prone to attacks as WSN are typically lacking interfere resilient hardware. Thus, purpose of veracity of facts and prestige of sensor nodes is critical for wireless sensor networks. Therefore, imminent gatherer nodes will be proficient of accomplishment additional cultivated data aggregation algorithms, so creating WSN little unresisting, as the performance of actual low power processors affectedly increases. Iterative filtering algorithms embrace inordinate capacity for such a resolution. The way of allocated the matching mass elements to information delivered by each source, such iterative algorithms concurrently assemble facts from several roots and deliver entrust valuation of these roots. Though suggestively extra substantial against collusion attacks beside the modest averaging techniques, are quiet vulnerable to a different cultivated attack familiarize. The existing literature is surveyed in this paper to have a study of iterative filtering techniques and a detailed comparison is provided. At the end of this paper new technique of improved iterative filtering is proposed with the help of literature survey and drawbacks found in the literature.
An overview of designing an induction heating system for domestic applications
Authors: Geetha V , Sivachidambaranathan V
Published: January 2019

The inherent benefit of the induction heating system leads to usage in the domestic applications. The design part of the coil has to be accurately manipulated to have highly qualified system. Discussion on the customisation of the coil and the converter section is elaborated such that the design relaying on the load variation, type of coil, rating required for the specified application. Thus the paper discusses about the design requirement on the domestic induction applications, depicting the criteria to be satisfied and the results are verified using the AC-AC converter fed induction heating system with the help of the equivalent circuit of the working coil and the work piece.
Adaptive filter-FLC integration for torque ripples minimization in PMSM using PSO
Authors: Ahmed Yasser , Hoballah Ayman
Published: January 2019

The article presents torque and flux ripples minimization based on adaptive filter. The adaptive filter coefficients optimized and adapted on line by using particle swarm optimization (PSO) technique. The proposed methodology applied on closed loop speed control based on direct torque control (DTC) for surface mounted permanent magnet synchronous motor (PMSM). Fuzzy logic controller (FLC) used as speed controller while proportional-integral (PI) controller used as torque and flux controllers. Second order infinite impulse response (IIR) filter is used for ripple reduction generated due to FLC. The drive system modeled using Matlab/Simulink software in order to dynamically evaluate the performance of the proposed drive system at different operating conditions. The results provide evidence that the adaptive filter-FLC integration with optimal coefficients minimizes torque and flux ripples with reduction of total harmonic distortion generated in the three-phase currents.
Integration of Reversing Voltage Multilevel Inverter Topology with High Voltage Gain boost Converter for Distributed Generation
Authors: Rao S. Nagaraja , Kumar D. V. Ashok , Babu Ch. Sai
Published: January 2019

The conventional energy sources available to us are on the verge of depletion. This depletion of conventional energy source leads to concentrate more on alternative energy sources. In this research, the focus is on the role of renewable energy sources (RES) in electrical power generation. Even though, the RES based plants produce power, we cannot directly connect it to the grid or loads. Because, the voltage ratings and nature supply of RES plants would not match with the load. Hence, this is a major issue for connecting RES plants to load or other utility. The power electronic converters are extensively being used as a link between load and supply. As most of the renewable energy power generation is DC in nature, the DC-DC converter is used to increase the voltage level and this DC must be converted to AC for grid connection. Therefore, inverters are used for DC to AC conversion. In this paper, the DC supply of renewable energy is connected to load by using cascade DC-DC converters along with a proposed reversing voltage (RV) multilevel inverter (MLI). The first DC-DC converter is used to enhance the voltage level with high gain and second converter is used to split the DC supply for inverter convenience. In this paper, proposed RV symmetrical and asymmetrical MLI generates 7, 9, 11, 13 and 15 levels with only ten power switches. In-phase level-shifted triangular carrier type sine pulse width modulation (PWM) technique is employed to trigger the commutating switches of proposed RV MLI. Switches of H-Bridge for reverse voltage appearance across the load are triggered by simple pulse generator. The circuits are modeled and simulated in MATLAB/SIMULINK software. Results are presented and discussed.
High Efficiency Harmonic Harvester Rectenna for Energy Storage Application
Authors: Kumar Deepak , Chaudhary Kalpana
Published: January 2019

This work presents harmonic harvester Rectenna integrated power management circuitry for improving RF-DC power conversion efficiency. The circuitry is developed for battery charging or energy storage application; resistance emulation method is used to realize a matching load resistance at output terminals. The proposed technique is useful for harvesting near maximum output power from the dual rectifiers (fundamental and harmonics) independently. Also, it delivers the combined maximal power to the energy storage cell. The power management module based on dual input buck-boost converter with simple open loop control is utilized.
Moderate Environmental Variation Across Generations Promotes the Evolution of Robust Solutions
Authors: Milano Nicola , Carvalho Jônata Tyska , Nolfi Stefano
Published: January 2019

Previous evolutionary studies demonstrated how robust solutions can be obtained by evaluating agents multiple times in variable environmental conditions. Here we demonstrate how agents evolved in environments that vary across generations outperform agents evolved in environments that remain fixed. Moreover, we demonstrate that best performance is obtained when the environment varies at a moderate rate across generations, that is, when the environment does not vary every generation but every N generations. The advantage of exposing evolving agents to environments that vary across generations at a moderate rate is due, at least in part, to the fact that this condition maximizes the retention of changes that alter the behavior of the agents, which in turn facilitates the discovery of better solutions. Finally, we demonstrate that moderate environmental variations are advantageous also from an evolutionary computation perspective, that is, from the perspective of maximizing the performance that can be achieved within a limited computational budget.
Logarithm Transformed Lomax Distribution with Applications
Authors: Nassar Mazen , Dey Sanku , Kumar Devendra
Published: January 2019

In this article, we introduce a new method for generating distributions which we refer to as logarithm transformed (LT) method. Some statistical properties of the LT method are established. Based on the LT method, we introduce a new generalization of the Lomax distribution that provides better fits than the Lomax distribution and some of its known generalizations. We refer to the new distribution as logarithmic transformed Lomax (LTL) distribution. Various properties of the LTL distribution, including explicit expressions for the moments, quantiles, moment generating function, incomplete moments, conditional moments, Rényi entropy, and order statistics are derived. It appears to be a distribution capable of allowing monotonically decreasing and upside-down bathtub shaped hazard rates depending on its parameters, so it turns out to be quite flexible for analysing non-negative real life data. We discuss the estimation of the model parameters by maximum likelihood method using random censoring scheme. The proposed distribution is utilized to fit a censored data set and the distribution is shown to be more appropriate to the data set than the compared distributions.

2010 Mathematics Subject Classification: 60E05, 60E10, 62E15.
Quantile-based Reliability Measures and Some Associated Stochastic Orderings
Authors: Kayal Suchandan , Sunoj S. M. , Vineshkumar B.
Published: January 2019

There are several statistical models which have explicit quantile functions, but do not have manageable cumulative distribution functions. For example, Govindarajulu, various forms of lambda, and power-Pareto distributions. Thus, to study the reliability measures for such kind of distributions, a quantile-based tool is essentially required. In this article, we consider quantile version of some well- known reliability measures in the reversed time scale. We study stochastic orders based on the reversed hazard quantile function and the mean inactivity quantile time function. Further, we discuss relative reversed hazard quantile function order, likelihood quantile ratio order, and elasticity quantile order. Connections between the newly proposed orders and the existing stochastic orders are established.

AMS 2010 Subject Classification: 60E15, 62E10
Parametric modeling based on the real geometry of glass fiber unidirectional non-crimp fabric
Authors: Wu Weili , Li Wei
Published: January 2019

Meso-structure modeling of fiber reinforcement is a critical step for predictions of the manufacturing process and mechanical properties of composites. In the work reported in this paper, a meso-scale model based on the real geometry of glass fiber non-crimp fabric (NCF) was developed, and an attempt for the parametric modeling has been made. First, the buckling of warp yarns due to the tension of stitching yarn has been considered, and the buckling can be described by a curve equation. In addition, cross-sectional characterizations of warp and weft yarns were studied via metallographic observations, and 3D models have been constructed. Second, the path of the polyester stitching yarn was extracted by the tracer fiber technique and fitted by the B-spline spline curve; this trace can be can be simplified to several equations in Matlab. Finally, the unit cell model has been assembled and the penetration has been checked for each component. In this study, a meso-scale model of NCF was accurately established which truly reflects the relationship among geometry and position of yarns, providing a precise geometric model for further study on compressive deformation and permeability prediction of NCF in the future.
A teacher’s guide to developing expertise through Ascending Intellectual Demand
Authors: El-Abd Maria
Published: January 2019

How can teachers adapt the curriculum to help advanced learners attain expertise? An abundance of research exists on the topic of expertise, exploring the traits students exhibit as they progress from the initial stages of novice-like uncertainty to the more confident stages of expertise. However, fewer researchers have demonstrated how teachers can use the curriculum to propel students along this continuum toward expertise. The purpose of the present article is to integrate conclusions of prior publications with an existing and effective model of curriculum, the Parallel Curriculum Model. The resulting guide is intended to accompany the ascending intellectual demand (AID) component of PCM and provide a proposal for a systematic way to consider and assess expertise, as well as guidance for using curriculum to help challenge advanced learners to perform at expert levels.
A dyadic model of investments: Partner effects on commitment
Authors: Coy Anthony E. , Davis Jody L. , Green Jeffrey D. , Etcheverry Paul E.
Published: January 2019

A dyadic approach to studying relationship dynamics yields considerably more insights than examining each partner separately. Yet relatively little research has examined dyadic models of commitment, despite commitment being essential to relationship persistence. Accordingly, we tested a dyadic version of the investment model of commitment. In two cross-sectional studies of couples and one experiment, we tested the role of partner investments and perceived partner investments as novel antecedents of commitment. Studies 1 and 2 demonstrated that greater partner investments were related to greater levels of individuals’ commitment, while controlling for individuals’ own satisfaction with, investments in, and alternatives to the relationship. Study 3 revealed that partner-reported investments predicted commitment independent of perceived partner investments. The findings advance the investment model beyond the individual level, emphasizing the need to examine dyadic elements of relationships.
Silencing of the TROP2 gene suppresses proliferation and invasion of hepatocellular carcinoma HepG2 cells
Authors: Zhang Jian , Ma Hai , Yang Liu , Yang Hongchun , He Zhenxing
Published: January 2019

Objectives

Overexpression of human trophoblast cell surface antigen 2 (Trop2) has been observed in many cancers; however, its roles in proliferation, apoptosis, migration, and invasion of hepatocellular carcinoma (HCC) remain unclear. Thus, this study aimed to characterize the function of Trop2 in HCC.

Methods

Trop2 protein expression was detected by immunohistochemistry in HCC tissues. Cell proliferation, apoptosis, and invasion were respectively measured by CCK-8, flow cytometry, Transwell, and wound healing assays. Expression levels of epithelial–mesenchymal transition-related proteins and Trop2 protein in HCC cell lines were detected by western blotting after silencing of the TROP2 gene.

Results

Trop2 protein was highly expressed in HCC tissues and HCC cell lines. Trop2 mRNA and protein expression levels decreased in HepG2 and HCCLM3 cells after transfection with Trop2 siRNA. Silencing of the TROP2 gene in HepG2 and HCCLM3 cells strongly inhibited cell proliferation and migration, while enhancing cell apoptosis. Investigation of the molecular mechanism revealed that silencing of the TROP2 gene suppressed epithelial–mesenchymal transition of HepG2 and HCCLM3 cells.

Conclusions

The results of the present study may improve understanding of the role of Trop2 in regulation of cell proliferation and invasion, and may aid in development of novel therapy for HCC.
The Oxygen Delivery Characteristics of the Hudson Oxy-one Face Mask
Authors: Milross J. , Young I. H. , Donnelly P.
Published: January 2019

The inspired oxygen fraction (FIO2) delivered by the Hudson Oxy-one face mask was measured under changing conditions of ventilation, oxygen flow rate to mask, and mask fit. A single trained subject sat in a body plethysmograph to measure ventilation and breathed at a constant rate of 15 per minute at three different tidal volumes, of approximately 0.3, 0.6, and 1.2 litres, from the mouthpiece in the plethysmograph. The Oxy-one face mask was fitted to a plaster-of Paris face model on the outside of the plethysmograph in a loose and then in a tight fashion. Oxygen concentration was continuously monitored from a point in the metal tube connecting the face model to the mouthpiece.

The tightly fitting mask demonstrated an orderly reduction in FIO2 as ventilation increased and oxygen flow rate to the mask decreased. The mean FIO2 at a ventilation of 4.5 l.min-1 and 8 l.min-1 oxygen flow was 78% and this fell to 27% at a ventilation of 16 l.min-1 and oxygen flow of 2 l.min-1. The loosely fitting mask demonstrated larger SD of measurements and lower mean maximum FIO2 values of 46 to 49% and these fell in an irregular fashion to similar minimum values as ventilation increased and oxygen flow decreased.

Although the precise definition of the FIO2 for each breath from the changing concentration during each inspiration was not possible, these results indicate that FIO2 changes in a predictable way as a function of ventilation and oxygen flow, if the mask is close fitting. This method could be conveniently used to study other oxygen delivery systems.
Clinical Experience with Atracurium during Prolonged Anaesthesia
Authors: Staun P. , Eriksson L. I. , Cederholm I. , Lennmarken C.
Published: January 2019

The pharmacodynamic properties of repeated injections of atracurium were studied in twenty-two patients. A control group received narcotic-based anaesthesia while another group received the same narcotic-based anaesthesia subsequently modified by the addition of 0.5% isoflurane. The twitch response of the adductor pollicis muscle was recorded after train-of-four (TOF) stimulation of the ulnar nerve at the wrist. Duration of effect and recovery time were measured. A bolus dose of atracurium (0.5 mg/kg b.w.) was given for tracheal intubation and maintenance doses of 0.2 mg/kg b.w. were given during anaesthesia at a TOF ratio of 0.25.

Mean duration of anaesthesia was 7.5 hours (range 3–19). In the control group mean duration of effect and mean recovery time remained unchanged (six doses studied). A noteworthy inter-individual variation was found. In the isoflurane group mean duration of effect increased from 36.1 (SD 6.3) minutes to 42.2 (SD 8.1) minutes (P<0.05) following the addition of isoflurane. Corresponding recovery times remained unchanged.

We conclude that during repeated administration of atracurium during narcotic-based anaesthesia, each patient shows a constant interval between requirements for maintenance doses of atracurium of 0.2 mg/kg b.w. Addition of 0.5% isoflurane causes a moderate prolongation of the duration of effect, but recovery time remains unchanged.
Preoperative Transdermal Hyoscine for the Prevention of Postoperative Nausea and Vomiting
Authors: Wilkinson A. R. , Frampton C. M. A , Glover P. W. , Davis F. M.
Published: January 2019

In a randomised, double-blind study, a transdermal patch containing either hyoscine or placebo was applied post-auricularly in 190 adult patients under 65 years old, seven to twelve hours prior to their undergoing minor orthopaedic or plastic surgery under thiopentone/nitrous oxide/halothane general anaesthesia. In the first 24 hours after surgery 34% of patients vomited. The incidence of nausea (31% vs 54%; P< 0.01) and the number of episodes of vomiting (66 vs 125; P< 0.05) during the first 24 hours were significantly less with hyoscine than with placebo. The hyoscine group required fewer doses of antiemetic than the placebo group (12 vs 27; P < 0.05). Side-effects were mild, the only difference between the two groups being the frequency of dry mouth immediately preoperatively. No differences were seen in the second 24 hours after surgery. We conclude that transdermal hyoscine is moderately effective in reducing the occurrence of postoperative nausea and vomiting following minor surgery.
Arterial and Mixed Venous Blood Gas Status during Apnoea of Intubation — Proof of the Christiansen-Douglas-Haldane Effect in Vivo
Authors: Mertzlufft F. O. , Brandt L. , Stanton-Hicks M. , Dick W.
Published: January 2019

The Christiansen-Douglas-Haldane effect, in short the Haldane effect, describes the dependence of the CO2 binding of blood on the degree of oxygenation of haemoglobin. Under the physiological conditions of an ‘open’ system between blood and alveoli the partial pressure of arterial C02 (PaCO2), must be less than that of mixed venous blood (P[Formula: see text]CO2).

During the unphysiological conditions of a ‘closed’ system, e.g. hyperoxic apnoea, i.e. continuous oxygen uptake without CO2 delivery by the lungs, the Paco2 will not only approximate the P[Formula: see text]CO2 but will even exceed it. Without the Haldane effect, rapid adjustment of Paco2 to P[Formula: see text]CO2 would be expected during apnoea due to the lack of CO2 excretion. If however, as undertaken in this study, ongoing oxygenation (high alveolar Po2 (PACO2) with concomitant lack of C02 delivery (apnoea, i. e. the C02 concentration remains constant) lead to a continuing sufficient oxygenation of blood during its passage through the lung capillaries, then this leads to a rightwards shift of the CO2 binding curve — the Haldane effect.

The resulting increase in Pco2 as shown here actually leads to an arterial-mixed venous CO2 partial pressure difference (a[Formula: see text]DPco2) of 2.8±1.8 mmHg. The results described substantiate for the first time the existence of the Haldane effect under clinical conditions.
Developing Operating Mode Distributions from Sparse Trajectories for Emission Estimation
Authors: Li Zufen , Song Guohua , Yu Xuejian , Yu Lei , He Weinan
Published: January 2019

To estimate local emissions accurately, it is necessary to develop site-specific operating mode (OpMode) distributions from local vehicle activity data at the 1-second interval (field continuous data/field data). Nowadays, large amounts of vehicle activity data are collected for navigation or traffic state monitoring. However, these data are not at the 1-second interval, they are at 2-second interval and above, and named the sparse vehicle activity data/sparse data in the paper. These data cannot be used to develop local OpMode distributions. Thus, the purpose of this study is to investigate how to use the sparse data at different time intervals, from 2 to 60 seconds, to develop OpMode distributions and emission factors (EFs) accurately. Analyzing the variations of acceleration rate, three trajectory reconstruction methods were developed to interpolate the sparse data into 1-second interval data: Cubic Spline Interpolation (CSI), Interpolation with Random Acceleration (IRA), and Cubic Spline + Interpolation with Random Acceleration (CSI+IRA). An application method of the sparse data was proposed by comparing the EFs of the field continuous data and those of the sparse data before and after the interpolation. This application method included three scenarios to accurately estimate CO2, CO, HC, and NOX emissions: (a) the sparse data at 2- to 3-second intervals can be directly used; (b) the sparse data at 4- to 5-second intervals can be used after interpolation by CSI; and (c) the sparse data from 6- to 60-second intervals can be used after interpolation by CSI + IRA.
Kinematics and Laxity of the Ankle Joint in Anatomic and Nonanatomic Anterior Talofibular Ligament Repair: A Biomechanical Cadaveric Study
Authors: Shoji Hiroaki , Teramoto Atsushi , Sakakibara Yuzuru , Kamiya Tomoaki , Watanabe Kota , Fujie Hiromichi , Yamashita Toshihiko
Published: January 2019

Background:

Although it is crucial to accurately identify the anterior talofibular ligament (ATFL) attachment site, it may not be feasible to fully observe the ATFL attachment site during arthroscopic surgery. As a result, the repair position might often be an unintentionally nonanatomic ATFL attachment site.

Hypothesis:

Anatomic ATFL repair restores kinematics and laxity to the ankle joint, while nonanatomic ATFL repair does not.

Study Design:

Controlled laboratory study.

Methods:

Seven normal fresh-frozen human cadaveric ankles were used. The ankles were tested with a 6 degrees of freedom robotic system. The following ankle states were evaluated: intact, ATFL injured, ATFL anatomic repair, and ATFL nonanatomic repair. The ATFL nonanatomic repair position was set 8 mm proximal from the center of the ATFL attachment site of the fibula. For each state, a passive plantarflexion (PF)–dorsiflexion (DF) kinematics test and a multidirectional loading test (anterior forces, inversion moment, and internal rotation moment) were performed.

Results:

The kinematics and laxity of the anatomic repair were not significantly different from those of the intact state. In nonanatomic repair, the inversion-eversion angle showed significant inversion (3.0°-3.4°) from 5° to 15° of DF, and the internal rotation–external rotation angle showed significant internal rotation (2.0°) at neutral PF-DF versus the intact state. In addition, internal rotation laxity was significantly increased (5.5°-5.8°) relative to the intact state in the nonanatomic repair at 30° and 15° of PF. There were no significant differences in anterior-posterior translation between the repairs.

Conclusion:

Although the anatomic ATFL repair state did not show significant differences in kinematics and laxity relative to the intact state, the nonanatomic ATFL repair state demonstrated significant inversion and internal rotation kinematics and internal rotation laxity when compared with the intact state.

Clinical Relevance:

Nonanatomic repair alters kinematics and laxity from the intact condition.
Lifetime Number of Perpetrators and Victim–Offender Relationship Status Per U.S. Victim of Intimate Partner, Sexual Violence, or Stalking
Authors: Peterson Cora , Liu Yang , Merrick Melissa , Basile Kathleen C. , Simon Thomas R.
Published: January 2019

The aim of this study was to describe the U.S. population-level prevalence of multiple perpetrator types (intimate partner, acquaintance, stranger, person of authority, or family member) per victim and to describe the prevalence of victim–offender relationship status combinations. Authors analyzed U.S. nationally representative data from noninstitutionalized adult respondents with self-reported lifetime exposure to intimate partner violence, sexual violence, or stalking in the 2012 National Intimate Partner and Sexual Violence Survey (NISVS). An estimated 142 million U.S. adults had some lifetime exposure to intimate partner violence, sexual violence, or stalking. An estimated 55 million victims (39% of total victims) had more than one perpetrator type during their lifetimes. A significantly higher proportion of female victims reported more than one perpetrator type compared with male victims (49% vs. 27%). Among both female and male victims with >1 perpetrator type, the most prevalent victim–offender relationship status combinations all included an intimate partner perpetrator. Many victims of interpersonal violence are subject to multiple perpetrator types during their lifetimes. Prevention strategies that address polyvictimization and protect victims from additional perpetrators can have a substantial and beneficial societal impact. Research on victim experiences to inform prevention strategies is strengthened by comprehensively accounting for lifetime victimizations.
Violence Against the Indigenous Women: Methodological and Ethical Recommendations for Research
Authors: Navarro-Mantas Laura , Ozemela Luana Marques-Garcia
Published: January 2019

The importance of more countries contributing to precise and comparable statistics on violence against women (VAW) is undeniable. Methodological adaptation is a very important aspect to increase the probability of women disclosing violence and safeguard their integrity. Research on VAW adapted to ethnic populations is scarce. Colombia has great ethnic diversity and is the country in the region with the second highest percentage of women reporting having suffered physical or sexual violence. However, statistics on VAW are limited, and no guidance or recommendations exist with respect to adapting the VAW research protocol to indigenous communities with unique forms of social organization. The indigenous Nasa community functions as a small society with its communal organization, own social norms, and indigenous customary law. In addition, the indigenous Nasa population has a worldview that is reflected in the way women suffer and face violence and discrimination. This article is based on a pilot survey that adapts and implements the WHO multicountry study’s survey methodology on women’s health and domestic VAW in three resguardos (communal lands) of the Nasa indigenous community in Colombia. The goal is to contribute to and improve the methodological adaptation of VAW research to cultural diversity, and simultaneously attempting to obtain high-quality data that can be comparable at the national and international levels. Recommendations for adaptation, ethical considerations, challenges, and implications for future studies with indigenous populations are discussed.
Improved empirical wavelet transform method based on spectrum trend for gearbox fault signal processing
Authors: Zhang Zheng , Wang Changming , Li Feng , Bao Yumei , Wu Huaping , Jiang Shaofei , Chai Guozhong
Published: January 2019

The empirical wavelet transform decomposes the signal by segmenting the Fourier spectrum and constructing an adaptive filter bank and then segments the spectrum by detecting the maximum value in the spectrum. However, the number of mono-components is unknown or difficult to confirm when processing actual gearbox fault signals, the result of decomposition will be neither reasonable nor conducive to demodulation analysis if the maximum value is concentrated in one component. To solve this problem, a concept of an amplitude modulation–frequency modulation signal in the form of a wave crest is proposed. The spectrum trend of the Fourier spectrum of signal is extracted by the empirical mode decomposition method, and then the number of mode components is presupposed and the spectrum is segmented according to the extracted spectrum trend. The extraction method of the spectrum trend based on improved empirical wavelet transform based on spectrum trend method is proposed for gearbox fault diagnosis. The experiment, including the vibration test platform of horizontal driving machine and the processing of experimental signals based on the improved empirical wavelet transform based on spectrum trend method are also given. According to the simulation and experiment results, it can be clearly found that the spectrum trend can describe the distribution of signal spectrum well, and the components obtained by the improved empirical wavelet transform based on spectrum trend method are more suitable than original empirical wavelet transform method for demodulation analysis.
Remission and low disease activity state (LDAS) are protective of intermediate and long-term outcomes in SLE patients. Results from LUMINA (LXXVIII), a multiethnic, multicenter US cohort
Authors: Alarcón G.S. , Ugarte-Gil M.F. , Pons-Estel G. , Vilá L.M. , Reveille J.D. , McGwin G.
Published: January 2019

Objective

The objective of this report is to determine the impact of remission and low disease activity state (LDAS) on damage accrual and mortality in systemic lupus erythematosus (SLE) patients.

Patients and methods

Visits from the Lupus in Minority populations: Nature vs. Nurture (LUMINA) cohort were categorized into remission (Systemic Lupus Activity Measure (SLAM) score = 0 and prednisone ≤ 5 mg/day and no immunosuppressants), LDAS ((not on remission), SLAM score ≤ 3, prednisone ≤ 7.5 mg/day, no immunosuppressants), or neither: active. Remission and LDAS visits were combined because of the relatively small number of remission visits. Their impact on damage accrual and mortality were examined by Poisson and logistic multivariable regressions adjusting for variables known to affect these outcomes.

Results

A total of 3879 visits for 558 patients (28% Caucasian, 37% African descent, 35% Hispanic) were studied. These visits corresponded to 71 in remission, 585 in LDAS, and 3223 active. The longer the percentage of time the patients were in remission/LDAS, the less damage accrual observed (rate ratio 0.1773 (95% confidence interval (CI) 0.1216 to 0.2584) p < 0.0001). A trend was observed in terms of mortality although statistical significance was not reached (odds ratio 0.303 (95% CI 0.063 to 1.456), p = 0.1360).

Conclusions

The longer the patient's state on Remission/LDAS, the less damage accrual that occurs. The protective effect on mortality was not statistically significant.
Damage Tolerance of Composite Materials Subject to Dynamic Flexural Tests
Authors: Lamy B. , Dixneuf E.
Published: January 2019

Experiments were conducted in order to study damage process generated on particular composite materials by low energy impacts. Woven and knitted reinforcement- structures were tested using a Charpy test. Experimental laws and analytical models characterising the damage evolution in these composite materials subjected to successive impacts are proposed and compared. Damage processes are different in both composites. The rupture of the woven composites is controlled by crackings and delaminations, the latter does not occur in the knitted ones. These analyses emphasise the interest of using knitted reinforcements in composite materials.
Structure and Properties of Bovine Hoof Horn
Authors: Baillie Caroline , Southam Chris , Buxton Anita , Pavan Priya
Published: January 2019

Fracture behaviour and bending stiffness of bovine hoof horn has been explored at a variety of hydration levels and in different orientations. The failure paths avoid fibre/tubule breakage where possible and hence preferred direction for cracks is along the direction of the intermediate filaments and in the direction of the tubules. The stiffness of bovine hoof horn becomes lower with increasing moisture content as would be expected and it is found that the difference is much greater than the influence of sample orientation. By measuring the stiffness at increasing water content it has been possible to display the whole range of properties from ductile to rather more brittle behaviour when very dry. The behaviour does not change until well below the natural water content of the fresh leaving a large margin of safety. The tests on bending samples within the plane of the outer wall, perpendicular to the tubules, did not show significant difference in stiffness values compared with tests parallel to the tubules, neither dry nor fully hydrated. It is concluded that the primary function of the intermediate filaments is to direct the cracks and provide fracture resistance, rather than changes in stiffness. However, further work is needed to establish the full structure/property relationships within this fascinating three-dimensional composite material so that we might learn how to incorporate some of its lessons into our composite structures.
A Computational Model of Viscoelastic Composite Materials for Ligament or Tendon Prostheses
Authors: Vena P.
Published: January 2019

A constitutive model and a finite element formulation for viscoelastic anisotropic materials subject to finite strains is expounded in this paper. The composite material is conceived as a matrix reinforced with stiff fibres. The constitutive relations are obtained by defining a strain energy function and a relaxation function for each constituent. By means of this approach, the viscoelastic properties of the material constituents can be taken into account and therefore different time dependent behaviour can be assigned to the matrix and to the reinforcing fibres. The response provided by this kind of constitutive formulation allows for the description of mechanical behaviour for either natural anisotropic tissues (such as tendons and ligaments) and for the composite materials which are currently adopted for tissue reconstruction. The main features of those mechanical properties observed in an ideal uniaxial test are: a non linear stress-strain response and a time dependent response which is observed in relaxation of stresses for a prescribed constant stretch and in a moderate strain rate dependence of the measured response.
An Iterative Effective Medium Approximation for Wave Dispersion and Attenuation Predictions in Particulate Composites
Authors: Tsinopoulos S.V , Verbis J. T. , Polyzos D.
Published: January 2019

This work deals with the dispersion and attenuation of elastic waves propagating in a random particle-reinforced composite. A new iterative effective medium approximation based on the single scattering consideration, for the quantitative estimation of wave dispersion and attenuation is proposed. The iterations are carried out via the classical dispersion relation of Foldy while the convergence of the iterative procedure is accomplished through a self-consistent condition proposed by Kim et al. [ 6 ]. The methodology is quite general and it works for any type of particles. The single scattering problem is solved numerically by means of an advanced boundary element code. Numerical results concerning the frequency dependent behaviour of the wave velocity and attenuation coefficient for three particular types of composites are presented. The results obtained are compared to those taken either experimentally or numerically by other investigators.
Analysis and Experimental Study for Steel Fibre Pullout from Cementitious Matrices
Authors: Karayannis C. G.
Published: January 2019

A model for the response of steel fibres embedded in a cementitious matrix and subjected to a pullout load, is presented. The pullout behaviour is dictated by the force transmission between fibre and matrix through an interfacial layer surrounding the fibre. Three distinct pullout load - bearing mechanisms are considered. The first one assumes perfect bond between matrix and fibre and is used for the description of the elastic stage when no real “slip” occurs. The second one is a transitional mechanism, which describes the behaviour at the onset of debonding, and the last one is a frictional dynamic pullout mechanism based on the matrix hydration shrinkage and a fibre - matrix misfit consideration. Pullout and pullthrough tests of steel fibres from cementitious matrices are also reported herein in order to investigate experimentally the pullout mechanisms, generate related data and use them complementary to the developed model. An attempt for the validation of the proposed model through comparisons between experimental data and analytical behaviour curves is also included.
Mechanical Properties of Sigma 1140+ Sic Fibres Prior and after Composite Processing
Authors: Gonzalez C. , Llorca J.
Published: January 2019

The effect of processing on the mechanical properties of Sigma 1140+ SiC fibres was studied through tensile tests carried out on pristine Sigma 1140+ SiC fibres and on fibres extracted from a Ti-6A1-4V-matrix composite. The elastic modulus and the tensile strength were computed after measuring carefully the fibre diameter. The characteristic fibre strength was reduced by 20% and the Weibull modulus by half during composite processing. The analysis of the fracture surfaces in the scanning electron microscope showed that the strength-limiting defects were located around the tungsten core in pristine fibres and predominantly at the surface in fibres extracted from the composite panels. These latter defects were nucleated by the mechanical stresses generated on the fibres during the panel consolidation.
Chopped Polyethylene Fibre Reinforced Ethylene-Butene Copolymers
Authors: Feigelshtein Diana , Harel Hannah , Lustiger Arnold , Marom Gad
Published: January 2019

This study verifies the option to process chopped polyethylene fibre reinforced polyolefins without causing fibre relaxation. It generates a new family of materials whose property range is as wide as the number of combinations of matrix choice and fibre content. The generic effect of the fibre on the mechanical properties is to turn a soft polyolefin matrix, characterised by low modulus and yield stress and high ductility, into a rigid, high strength composite material.
Impact of Adhesively Bonded Composite Joints with Edge Effect
Authors: Farrow I.R. , Potter K. , Fisher A. , Kelly M.
Published: January 2019

A pilot project has been carried out to investigate the effect of impact on single-lap bonded composite joints based on AS4-8552 laminates and Cybond BR4535A adhesive. Low velocity impacts at an energy level sufficient to cause barely visible impact damage, were conducted on single lap joint specimens at different joint positions. Impact caused delaminations in the upper and lower laminates and localised through-thickness cracking in the adhesive. Residual tensile joint strengths of the impacted joint specimens with near-edge damage were reduced to approximately 50% of the un-impacted value. Failure surface inspections revealed localised through-thickness adhesive shear cracking as a governor of the original impact delamination pattern in the laminates and laminate delamination as the cause of ultimate tensile failure.
Effect of Consolidation Degree on the Failure Generated Acoustic Emission Response of Discontinuous Glass Fibre Mat-Reinforced Polypropylenes
Authors: Romhany Gabor , Czigany Tibor , Benevolenski Oleg I. , Karger-Kocsis Jozsef
Published: January 2019

The failure behaviour of partially and fully consolidated discontinuous glass fibre (GF) mat-reinforced thermoplastic polypropylene (GMT-PP) of various densities but with the same GF content was studied using the acoustic emission (AE) technique. The AE amplitude histograms were used to trace changes in the failure mode versus loading history and consolidation degree. AE amplitudes were clustered in three groups representing fibre debonding, pull-out and fracture events the occurrence of which was substantiated by fractografic inspection.
Thermal Expansion Anisotropy in Injection-Moulded Natural-Fibre Composites
Authors: Cichocki F. R.
Published: January 2019

Recently much effort has been devoted to the development of natural-fibre composites produced via injection moulding. Although several processing-cost benefits may be associated with the injection moulding process, the microstructures of injection-moulded composites can be quite complex and anisotropic. In this study, the thermal expansion anisotropy that may develop in injection moulded natural-fibre composites has been investigated. A thermal mechanical analyser (TMA) has been employed to determine the thermal expansion properties of jute and sisal-fibre reinforced polypropylene composites injection-moulded into the form of tensile bars and disks. Measurements indicated that thermal expansion coefficients of tensile bars in the melt-flow direction may be 5 to 7 times less than thermal expansion coefficients in the cross-flow direction.
Dilation of Ti-6Al-4V/HA Composite Tensile Parts
Authors: Thian E. S. , Loh N. H. , Khor K. A. , Tor S. B.
Published: January 2019

Prior to the actual sintering process, a dilatometry study is performed to provide basic information and guidelines. This paper studies the effects of three sintering factors: sintering temperature, heating rate and holding time, on the densification rate of Ti-6Al-4V/HA composite parts. According to the in-situ test results, suitable values for the sintering factors can then be established.
Effect of Fabrication Processes on the Deformation and Fracture Behaviour of Sic/Al Composites
Authors: Ding Boxiong , Ding J. L. , Antolovich Stephen D. , Cho S. C.
Published: January 2019

The purpose of this research is to investigate the effects of microstructural parameters as a result of three different processing methods on the deformation and fracture properties of SiC/Al composites. The influences of heat treatment are also investigated. It was found that without heat treatment, the SiC reinforcement phase significantly improved the strength of the composite compared to the Al matrix material. However, the strengths of the heat-treated composites were roughly in the same range as those of heat-treated Al alloy. The ball-milled composite has higher strength, but lower fracture toughness compared to the powder and flake composites. Between the latter two, the powder composite has higher toughness.
Full Scale Structural Experimental Investigation of an E-Glass/Epoxy Composite Wind Turbine Blade
Authors: Kong C. , Sugiyama Y. , Lee J. , Soutis C.
Published: January 2019

A structural test of a new wind turbine rotor blade was performed to evaluate design uncertainties due to material defects, analytical assumptions and production process, and quantify their effect on its structural integrity. In the full-scale static strength test, the measuring parameters were the blade weight, location of centre of gravity, in-plane strains, deflections and failure loads. Performing a three-point bending test of the full-scale (size) blade simulated the aerodynamic load experienced by the rotor blade. Analytical predictions for mass of the blade, centre of gravity location, blade tip deflection and the first flap-wise natural frequency were in good agreement with the measured values. The difference was less than 4%, indicating that the blade response was accurately modelled by a linear analysis. The axial strain of the blade skin was also measured at several blade stations: 5.56 m, 11.59 m and 13.43 m at an applied load of 20%, 40%, 60%, 80% and 100% of the maximum design load. Acceptable agreement was achieved between experimental and theoretical strain results, using the Tsai-Wu failure criterion.