Open AccessFeature PaperArticle
A Gaussian Process Data Modelling and Maximum Likelihood Data Fusion Method for Multi-Sensor CMM Measurement of Freeform Surfaces
Appl. Sci. 2016, 6(12), 409; doi:10.3390/app6120409 (registering DOI) -
Abstract
Nowadays, the use of freeform surfaces in various functional applications has become more widespread. Multi-sensor coordinate measuring machines (CMMs) are becoming popular and are produced by many CMM manufacturers since their measurement ability can be significantly improved with the help of different kinds
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Nowadays, the use of freeform surfaces in various functional applications has become more widespread. Multi-sensor coordinate measuring machines (CMMs) are becoming popular and are produced by many CMM manufacturers since their measurement ability can be significantly improved with the help of different kinds of sensors. Moreover, the measurement accuracy after data fusion for multiple sensors can be improved. However, the improvement is affected by many issues in practice, especially when the measurement results have bias and there exists uncertainty regarding the data modelling method. This paper proposes a generic data modelling and data fusion method for the measurement of freeform surfaces using multi-sensor CMMs and attempts to study the factors which affect the fusion result. Based on the data modelling method for the original measurement datasets and the statistical Bayesian inference data fusion method, this paper presents a Gaussian process data modelling and maximum likelihood data fusion method for supporting multi-sensor CMM measurement of freeform surfaces. The datasets from different sensors are firstly modelled with the Gaussian process to obtain the mean surfaces and covariance surfaces, which represent the underlying surfaces and associated measurement uncertainties. Hence, the mean surfaces and the covariance surfaces are fused together with the maximum likelihood principle so as to obtain the statistically best estimated underlying surface and associated measurement uncertainty. With this fusion method, the overall measurement uncertainty after fusion is smaller than each of the single-sensor measurements. The capability of the proposed method is demonstrated through a series of simulations and real measurements of freeform surfaces on a multi-sensor CMM. The accuracy of the Gaussian process data modelling and the influence of the form error and measurement noise are also discussed and demonstrated in a series of experiments. The limitations and some special cases are also discussed, which should be carefully considered in practice. Full article
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Open AccessArticle
Hyperspectral Imaging to Evaluate the Effect of IrrigationWater Salinity in Lettuce
Appl. Sci. 2016, 6(12), 412; doi:10.3390/app6120412 (registering DOI) -
Abstract
Salinity is one of the most important stress factors in crop production, particularly in arid regions. This research focuses on the effect of salinity on the growth of lettuce plants; three solutions with different levels of salinity were considered and compared (S1 =
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Salinity is one of the most important stress factors in crop production, particularly in arid regions. This research focuses on the effect of salinity on the growth of lettuce plants; three solutions with different levels of salinity were considered and compared (S1 = 50, S2 = 100 and S3 = 150 mM NaCl) with a control solution (Ct = 0 mM NaCl). The osmotic potential and water content of the leaves were measured, and hyperspectral images of the surfaces of 40 leaves (10 leaves per treatment) were taken after two weeks of growth. The mean spectra of the leaves (n = 32,000) were pre-processed by means of a Savitzky–Golay algorithm and standard normal variate normalization. Principal component analysis was then performed on a calibration set of 28 mean spectra, yielding an initial model for salinity effect detection. A second model was subsequently proposed based on an index computing an approximation to the second derivative at the red edge region. Both models were applied to all the hyperspectral images to obtain the corresponding artificial images, distinguishing between the 28 that were used to extract the calibration mean spectra and the rest that constituted an external validation. Those virtual images were studied using analysis of variance in order to compare their ability for detecting salinity effects on the leaves. Both models showed significant differences between each salinity level, and the hyperspectral images allowed observations of the distribution of the salinity effects on the leaf surfaces, which were more intense in the areas distant from the veins. However, the index-based model is simpler and easier to apply because it is based solely on the reflectance at three different wavelengths, thus allowing for the implementation of less expensive multispectral devices. Full article
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Open AccessArticle
Tunable Degradation Rate and Favorable Bioactivity of Porous Calcium Sulfate Scaffolds by Introducing Nano-Hydroxyapatite
Appl. Sci. 2016, 6(12), 411; doi:10.3390/app6120411 (registering DOI) -
Abstract
The bone scaffolds should possess suitable physicochemical properties and osteogenic activities. In this study, porous calcium sulfate (CaSO4) scaffolds were fabricated successfully via selected laser sintering (SLS). Nano-hydroxyapatite (nHAp), a bioactive material with a low degradation rate, was introduced into CaSO
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The bone scaffolds should possess suitable physicochemical properties and osteogenic activities. In this study, porous calcium sulfate (CaSO4) scaffolds were fabricated successfully via selected laser sintering (SLS). Nano-hydroxyapatite (nHAp), a bioactive material with a low degradation rate, was introduced into CaSO4 scaffolds to overcome the overquick absorption. The results demonstrated that nHAp could not only control the degradation rate of scaffolds by adjusting their content, but also improve the pH environment by alleviating the acidification progress during the degradation of CaSO4 scaffolds. Moreover, the improved scaffolds were covered completely with the apatite spherulites in simulated body fluid (SBF), showing their favorable bioactivity. In addition, the compression strength and fracture toughness were distinctly enhanced, which could be ascribed to large specific area of nHAp and the corresponding stress transfer. Full article
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Open AccessReview
Assessing the Dynamic Performance of Microbots in Complex Fluid Flows
Appl. Sci. 2016, 6(12), 410; doi:10.3390/app6120410 (registering DOI) -
Abstract
The use of microbots in biomedicine is a powerful tool that has been an object of study in the last few years. In the special case of using these microdevices in the human circulatory system to remove clots or to deliver drugs, the
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The use of microbots in biomedicine is a powerful tool that has been an object of study in the last few years. In the special case of using these microdevices in the human circulatory system to remove clots or to deliver drugs, the complex nature of blood flow must be taken into account for their proper design. The dynamic performance, defined in this context as the quantification of the disturbance of the flow around an object (which is essentially dependent on the microbot morphology and the rheological characteristics of the fluid) should be improved in order to diminish the damage inside the patient body and to increase the efficiency when they swim through the main veins or arteries. In this article, different experimental techniques (micro-Particle Image Velocimetry, flow visualization, pressure drop measurements, etc.) are analyzed to assess their dynamic performance when they swim through the human body immersed in complex fluid flows. This article provides a useful guide for the characterization of the dynamic performance of microbots and also highlights the necessity to consider the viscoelastic character of blood in their design. Full article
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Open AccessArticle
Characterization of Transition-Metal Oxide Deposition on Carbon Electrodes of a Supercapacitor
Appl. Sci. 2016, 6(12), 413; doi:10.3390/app6120413 (registering DOI) -
Abstract
In order to fabricate the composite electrodes of a supercapacitor, transition-metal oxide materials NiO and WO3 were deposited on carbon electrodes by electron beam evaporation. The influences of various transition-metal oxides, scan rates of cyclic voltammograms (CVs), and galvanostatic charge/discharge tests on
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In order to fabricate the composite electrodes of a supercapacitor, transition-metal oxide materials NiO and WO3 were deposited on carbon electrodes by electron beam evaporation. The influences of various transition-metal oxides, scan rates of cyclic voltammograms (CVs), and galvanostatic charge/discharge tests on the characteristics of supercapacitor were studied. The charge/discharge efficiency and the lifetime of the composite electrodes were also investigated. It was found that the composite electrodes exhibited more favorable capacitance properties than those of the carbon electrodes at high scan rates. The results revealed the promotion of the capacitance property of the supercapacitor with composite electrode and the improving of the decay property in capacitance at high scan rate. In addition, the charge/discharge efficiency is close to 100% after 5000 cycles, and the composite electrode retains strong adhesion between the electrode material and the substrate. Full article
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Open AccessArticle
Enhancing the Drag Reduction Phenomenon within a Rotating Disk Apparatus Using Polymer-Surfactant Additives
Appl. Sci. 2016, 6(12), 355; doi:10.3390/app6120355 (registering DOI) -
Abstract
Pipelines and tubes play important roles in transporting economic liquids, such as water, petroleum derivatives, and crude oil. However, turbulence reduces the initial flow rate at which liquids are pumped, thereby making liquid transportation through pipelines inefficient. This study focuses on enhancing the
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Pipelines and tubes play important roles in transporting economic liquids, such as water, petroleum derivatives, and crude oil. However, turbulence reduces the initial flow rate at which liquids are pumped, thereby making liquid transportation through pipelines inefficient. This study focuses on enhancing the drag reduction (DR) phenomenon within a rotating disk apparatus (RDA) using polymer-surfactant additives. The complex mixture of polyisobutylene (PIB) and sodium dioctyl sulfosuccinate (SDS) was used. These materials were tested individually and as a complex mixture in RDA at various concentrations and rotational speeds (rpm). The morphology of this complex was investigated using transmission electronic microscopy (TEM). The reduction of the degradation level caused by the continuous circulation of surfactant additives in RDA could improve the long-term DR level. Experimental result shows that the maximum %DR of the complex mixture was 21.455% at 3000 rpm, while the PIB and SDS were 19.197% and 8.03%, respectively. Therefore, the complex mixture had better performance than these substances alone and were highly dependent on the alkyl chain of the surfactant. Full article
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Open AccessArticle
An Investigation of the Methods of Logicalizing the Code-Checking System for Architectural Design Review in New Taipei City
Appl. Sci. 2016, 6(12), 407; doi:10.3390/app6120407 (registering DOI) -
Abstract
The New Taipei City Government developed a Code-checking System (CCS) using Building Information Modeling (BIM) technology to facilitate an architectural design review in 2014. This system was intended to solve problems caused by cognitive gaps between designer and reviewer in the design review
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The New Taipei City Government developed a Code-checking System (CCS) using Building Information Modeling (BIM) technology to facilitate an architectural design review in 2014. This system was intended to solve problems caused by cognitive gaps between designer and reviewer in the design review process. Along with considering information technology, the most important issue for the system’s development has been the logicalization of literal building codes. Therefore, to enhance the reliability and performance of the CCS, this study uses the Fuzzy Delphi Method (FDM) on the basis of design thinking and communication theory to investigate the semantic difference and cognitive gaps among participants in the design review process and to propose the direction of system development. Our empirical results lead us to recommend grouping multi-stage screening and weighted assisted logicalization of non-quantitative building codes to improve the operability of CCS. Furthermore, CCS should integrate the Expert Evaluation System (EES) to evaluate the design value under qualitative building codes. Full article
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Open AccessArticle
Numerical Characterization of Protein Sequences Based on the Generalized Chou’s Pseudo Amino Acid Composition
Appl. Sci. 2016, 6(12), 406; doi:10.3390/app6120406 (registering DOI) -
Abstract
The technique of comparison and analysis of biological sequences is playing an increasingly important role in the field of Computational Biology and Bioinformatics. One of the key steps in developing the technique is to identify an appropriate manner to represent a biological sequence.
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The technique of comparison and analysis of biological sequences is playing an increasingly important role in the field of Computational Biology and Bioinformatics. One of the key steps in developing the technique is to identify an appropriate manner to represent a biological sequence. In this paper, on the basis of three physical–chemical properties of amino acids, a protein primary sequence is reduced into a six-letter sequence, and then a set of elements which reflect the global and local sequence-order information is extracted. Combining these elements with the frequencies of 20 native amino acids, a (21+λ) dimensional vector is constructed to characterize the protein sequence. The utility of the proposed approach is illustrated by phylogenetic analysis and identification of DNA-binding proteins. Full article
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Open AccessArticle
Sizing Subsurface Defects in Metallic Plates by Square Pulse Thermography Using an Oriented Gradient Map
Appl. Sci. 2016, 6(12), 389; doi:10.3390/app6120389 -
Abstract
We developed a new approach for sizing subsurface defects in the square pulse thermography of metallic plates by employing the oriented gradient of histograms. To size defects with high accuracies is still a challenge in infrared (IR) thermography today. Especially for blurry defects,
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We developed a new approach for sizing subsurface defects in the square pulse thermography of metallic plates by employing the oriented gradient of histograms. To size defects with high accuracies is still a challenge in infrared (IR) thermography today. Especially for blurry defects, accurate sizing of them is difficult with existing methods. The oriented gradient of histograms, which is used in the successful probability of boundary (Pb) contour detector in natural image processing literature, is employed in this work to improve the sizing accuracy in square pulse thermography. Experiments on a corroded steel plate with flat blind holes have verified the effectiveness of the proposed approach to size defects. Experimental results show that the proposed approach can size distinct and blurry defects with high accuracies. Comparison research is also implemented between the proposed approach and other sizing methods. The comparison results show that the proposed approach is superior to existing methods. Full article
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Open AccessArticle
Prediction of Cone Crusher Performance Considering Liner Wear
Appl. Sci. 2016, 6(12), 404; doi:10.3390/app6120404 -
Abstract
Cone crushers are used in the aggregates and mining industries to crush rock material. The pressure on cone crusher liners is the key factor that influences the hydraulic pressure, power draw and liner wear. In order to dynamically analyze and calculate cone crusher
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Cone crushers are used in the aggregates and mining industries to crush rock material. The pressure on cone crusher liners is the key factor that influences the hydraulic pressure, power draw and liner wear. In order to dynamically analyze and calculate cone crusher performance along with liner wear, a series of experiments are performed to obtain the crushed rock material samples from a crushing plant at different time intervals. In this study, piston die tests are carried out and a model relating compression coefficient, compression ratio and particle size distribution to a corresponding pressure is presented. On this basis, a new wear prediction model is proposed combining the empirical model for predicting liner wear with time parameter. A simple and practical model, based on the wear model and interparticle breakage, is presented for calculating compression ratio of each crushing zone along with liner wear. Furthermore, the size distribution of the product is calculated based on existing size reduction process model. A method of analysis of product size distribution and shape in the crushing process considering liner wear is proposed. Finally, the validity of the wear model is verified via testing. The result shows that there is a significant improvement of the prediction of cone crusher performance considering liner wear as compared to the previous model. Full article
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Open AccessArticle
Personality Traits Bias the Perceived Quality of Sonic Environments
Appl. Sci. 2016, 6(12), 405; doi:10.3390/app6120405 -
Abstract
There have been few empirical investigations of how individual differences influence the perception of the sonic environment. The present study included the Big Five traits and noise sensitivity as personality factors in two listening experiments (n = 43, n = 45). Recordings
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There have been few empirical investigations of how individual differences influence the perception of the sonic environment. The present study included the Big Five traits and noise sensitivity as personality factors in two listening experiments (n = 43, n = 45). Recordings of urban and restaurant soundscapes that had been selected based on their type were rated for Pleasantness and Eventfulness using the Swedish Soundscape Quality Protocol. Multivariate multiple regression analysis showed that ratings depended on the type and loudness of both kinds of sonic environments and that the personality factors made a small yet significant contribution. Univariate models explained 48% (cross-validated adjusted R2) of the variation in Pleasantness ratings of urban soundscapes, and 35% of Eventfulness. For restaurant soundscapes the percentages explained were 22% and 21%, respectively. Emotional stability and noise sensitivity were notable predictors whose contribution to explaining the variation in quality ratings was between one-tenth and nearly half of the soundscape indicators, as measured by squared semipartial correlation. Further analysis revealed that 36% of noise sensitivity could be predicted by broad personality dimensions, replicating previous research. Our study lends empirical support to the hypothesis that personality traits have a significant though comparatively small influence on the perceived quality of sonic environments. Full article
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Open AccessArticle
A Novel Ropes-DrivenWideband Piezoelectric Vibration Energy Harvester
Appl. Sci. 2016, 6(12), 402; doi:10.3390/app6120402 -
Abstract
This paper presents a novel piezoelectric vibration energy harvester (PVEH) in which a high-frequency generating beam (HFGB) is driven by an array of low-frequency driving beams (LFDBs) using ropes. Two mechanisms based on frequency upconversion and multimodal harvesting work together to broaden the
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This paper presents a novel piezoelectric vibration energy harvester (PVEH) in which a high-frequency generating beam (HFGB) is driven by an array of low-frequency driving beams (LFDBs) using ropes. Two mechanisms based on frequency upconversion and multimodal harvesting work together to broaden the frequency bandwidth of the proposed vibration energy harvester (VEH). The experimental results show that the output power of generating beam (GB) remains unchanged with the increasing number of driving beams (DBs), compared with the traditional arrays of beams vibration energy harvester (AB-VEH), and the output power and bandwidth behavior can be adjusted by parameters such as acceleration, rope margin, and stiffness of LFDBs, which shows the potential to achieve unlimited wideband vibration energy-harvesting for a variable environment. Full article
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Open AccessArticle
A Novel Mechanical Fault Diagnosis Scheme Based on the Convex 1-D Second-Order Total Variation Denoising Algorithm
Appl. Sci. 2016, 6(12), 403; doi:10.3390/app6120403 -
Abstract
Convex 1-D first-order total variation (TV) denoising is an effective method for eliminating signal noise, which can be defined as convex optimization consisting of a quadratic data fidelity term and a non-convex regularization term. It not only ensures strict convex for optimization problems,
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Convex 1-D first-order total variation (TV) denoising is an effective method for eliminating signal noise, which can be defined as convex optimization consisting of a quadratic data fidelity term and a non-convex regularization term. It not only ensures strict convex for optimization problems, but also improves the sparseness of the total variation term by introducing the non-convex penalty function. The convex 1-D first-order total variation denoising method has greater superiority in recovering signals with flat regions. However, it often produces undesirable staircase artifacts. Moreover, actual denoising efficacy largely depends on the selection of the regularization parameter, which is utilized to adjust the weights between the fidelity term and total variation term. Using this, algorithms based on second-order total variation regularization and regularization parameter optimization selection are proposed in this paper. The parameter selection index is determined by the permutation entropy and cross-correlation coefficient to avoid the interference by human experience. This yields the convex 1-D second-order total variation denoising method based on the non-convex framework. Comparing with traditional wavelet denoising and first-order total variation denoising, the validity of the proposed method is verified by analyzing the numerical simulation signal and the vibration signal of fault bearing in practice. Full article
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Open AccessArticle
Discrete-Time Sliding Mode Filter with Adaptive Gain
Appl. Sci. 2016, 6(12), 400; doi:10.3390/app6120400 -
Abstract
In feedback control of mechatronic systems, sensor signals are usually noisy and uncertain because of measurement errors and environmental disturbances. Such uncertainty and noise of feedback signals may cause instability of the controlled systems. This paper presents a new model-free discrete-time sliding mode
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In feedback control of mechatronic systems, sensor signals are usually noisy and uncertain because of measurement errors and environmental disturbances. Such uncertainty and noise of feedback signals may cause instability of the controlled systems. This paper presents a new model-free discrete-time sliding mode filter for effectively removing noise by balancing the tradeoff between the filtering smoothness and the suppression of delay. The presented filter is an extension of a sliding mode filter (Jin et al. Real-time quadratic sliding mode filter for removing noise. Adv. Robot., 2012) by including an adaptive gain, of which value is determined in a similar way to that of a first-order adaptive windowing filter (Janabi-Sharifi et al. Discrete-time adaptive windowing for velocity estimation. IEEE Trans. Control Syst. Technol., 2000). The effectiveness of the presented filter is validated through numerical examples and experiments. Full article
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Open AccessArticle
The Influence of Process Parameters on the Surface Roughness of a 3D-Printed Co–Cr Dental Alloy Produced via Selective Laser Melting
Appl. Sci. 2016, 6(12), 401; doi:10.3390/app6120401 -
Abstract
Selective laser melting (SLM), used to fabricate metallic objects with high geometrical complexity, is currently of increasing interest to the fields of medicine and dentistry. SLM-fabricated products should have highly smooth surfaces to minimize the use of post-processing procedures such as finishing and
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Selective laser melting (SLM), used to fabricate metallic objects with high geometrical complexity, is currently of increasing interest to the fields of medicine and dentistry. SLM-fabricated products should have highly smooth surfaces to minimize the use of post-processing procedures such as finishing and polishing. This study investigated the effect of various laser process parameters (laser power, scan rate, and scan-line spacing) on the surface roughness of a Co–Cr dental alloy that was three-dimensionally (3D) constructed via SLM. Initially, a single-line formation test was used to determine the optimal laser power (200 W) and scan rate (128.6 mm/s) that resulted in beads with an optimal profile. During subsequent multi-layer formation tests, the 3D Co–Cr body with the smoothest surface was produced using a scan-line spacing of 100 μm. The findings of this study show that laser process parameters have crucial effects on the surface quality of SLM-fabricated Co–Cr dental alloys. Full article
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Open AccessArticle
Photoacoustic Tomography Imaging of the Adult Zebrafish by Using Unfocused and Focused High-Frequency Ultrasound Transducers
Appl. Sci. 2016, 6(12), 392; doi:10.3390/app6120392 -
Abstract
The zebrafish model provides an essential platform for the study of human diseases or disorders due to the possession of about 87% homologous genes with human. However, it is still very challenging to noninvasively visualize the structure and function of adult zebrafish based
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The zebrafish model provides an essential platform for the study of human diseases or disorders due to the possession of about 87% homologous genes with human. However, it is still very challenging to noninvasively visualize the structure and function of adult zebrafish based on available optical imaging techniques. In this study, photoacoustic tomography (PAT) was utilized for high-resolution imaging of adult zebrafish by using focused and unfocused high-frequency (10 MHz) ultrasound transducers. We examined and compared the imaging results from the two categories of transducers with in vivo experimental tests, in which we discovered that the unfocused transducer is able to identify the inner organs of adult zebrafish with higher contrast but limited regional resolution, whereas the findings from the focused transducer were with high resolution but limited regional contrast for the recovered inner organs. Full article
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Open AccessArticle
Analysis of Psychoacoustic and Vibration-Related Parameters to Track the Reasons for Health Complaints after the Introduction of New Tramways
Appl. Sci. 2016, 6(12), 398; doi:10.3390/app6120398 -
Abstract
Background: A change to new tramways in Graz (Austria) led to severe complaints in residential areas. To understand the underlying reasons for these complaints, a systematic measurement campaign was designed. Methods: Six locations in Graz and two locations in a comparably sized city
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Background: A change to new tramways in Graz (Austria) led to severe complaints in residential areas. To understand the underlying reasons for these complaints, a systematic measurement campaign was designed. Methods: Six locations in Graz and two locations in a comparably sized city were selected. Parallel indoor recordings of sound and vibrations were conducted from 8:00 p.m. to 8:00 a.m. (due to sleep problems) at all locations. Results: Vibration levels remained below the limits of the Austrian standard (Wm-weighting) although variability was observed among sites, tram types and pass-bys. A complex characteristic of the acoustic feature space was found with A-weighting (differences between A- and C-weighting of more than 15 dB were observed). C-weighted background to peak noise ratios clearly distinguished “old” from “new” trams. Psychoacoustic indices indicated a high variability between locations and tram types. Roughness and loudness was higher in “new” versus “old” trams at most locations. “New” trams exhibited high sharpness values and variability, especially at higher speeds—when compared with trams from a control city. Conclusions: Standard indicators of sound and vibration were not sensitive enough to uncover the reasons for the complaints. Only the integrated analysis of the ambient soundscape (high signal-to-noise-ratio), the more noticeable sound (in psychoacoustic terms) and the observed high variance of the immissions provided guidance to implement appropriate technical solutions. Full article
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Open AccessArticle
Ultrasound Navigation for Transcatheter Aortic Stent Deployment Using Global and Local Information
Appl. Sci. 2016, 6(12), 391; doi:10.3390/app6120391 -
Abstract
An ultrasound (US) navigation system using global and local information is presented for transcatheter aortic stent deployment. The system avoids the use of contrast agents and radiation required in traditional fluoroscopically-guided procedures and helps surgeons precisely visualize the surgical site. To obtain a
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An ultrasound (US) navigation system using global and local information is presented for transcatheter aortic stent deployment. The system avoids the use of contrast agents and radiation required in traditional fluoroscopically-guided procedures and helps surgeons precisely visualize the surgical site. To obtain a global 3D (three-dimensional) navigation map, we use magnetic resonance (MR) to provide a 3D context to enhance 2D (two-dimensional) US images through image registration. The US images are further processed to obtain the trajectory of interventional catheter. A high-resolution aortic model is constructed by using trajectory and segmented intravascular ultrasound (IVUS) images. The constructed model reflects morphological characteristics of the aorta to provide local navigation information. Our navigation system was validated using in vitro phantom of heart and aorta. The mean target registration error is 2.70 mm and the average tracking error of the multi-feature particle filter is 0.87 mm. These results confirm that key parts of our navigation system are effective. In the catheter intervention experiment, the vessel reconstruction error of local navigation is reduced by 80% compared to global navigation. Moreover, the targeting error of the navigation combining global and local information is reduced compared to global navigation alone (1.72 mm versus 2.87 mm). Thus, the US navigation system which integrates the large view of global navigation and high accuracy of local navigation can facilitate transcatheter stent deployment. Full article
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Open AccessArticle
A Novel Hybrid Semi-Active Mass Damper Configuration for Structural Applications
Appl. Sci. 2016, 6(12), 397; doi:10.3390/app6120397 -
Abstract
In this paper, a novel energy- and cost-efficient hybrid semi-active mass damper configuration for use in structural applications has been developed. For this task, an arrangement of both active and semi-active control components coupled with appropriate control algorithms are constructed and their performance
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In this paper, a novel energy- and cost-efficient hybrid semi-active mass damper configuration for use in structural applications has been developed. For this task, an arrangement of both active and semi-active control components coupled with appropriate control algorithms are constructed and their performance is evaluated on both single and multi-degree of freedom structures for which practical constraints such as stroke and force saturation limits are taken into account. It is shown that under both free and forced vibrations, the novel device configuration outperforms its more conventional passive and semi-active counterparts, while at the same time achieving performance gains similar to the active configuration at considerably less energy and actuation demands, satisfying both strict serviceability and sustainability requirements often found to govern most modern structural applications. Full article
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Open AccessArticle
A Novel Mobile Communications Authentication Scheme with Roaming Service and User Anonymity
Appl. Sci. 2016, 6(12), 393; doi:10.3390/app6120393 -
Abstract
Many novel, effective, and efficient applications and networking services are being developed for the Social Internet of Things. Recently, Li proposed a more secure and efficient authentication scheme with roaming service and user anonymity for mobile communications. The security analysis and discussion of
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Many novel, effective, and efficient applications and networking services are being developed for the Social Internet of Things. Recently, Li proposed a more secure and efficient authentication scheme with roaming service and user anonymity for mobile communications. The security analysis and discussion of the agreement phase is sufficiently safe; however, an attacker can intercept the identity of a mobile user’s home agent in the authentication phase. By using this information, the attacker can mount distributed denial-of-service attacks in the roaming phase through replay attacks targeting the network’s foreign agent and mobile user’s home agent by using their corresponding session keys. Li’s method also has some shortcomings regarding anonymity that we aim to address. To overcome these issues, this study proposes an elliptic curve–based wireless roaming anonymous login method for the authentication phase. The problems faced in the roaming phase are resolved, and this approach provides balanced session key computation between senders and receivers. Burrows-Abadi-Needham logic (BAN-logic) is used to verify the security of the proposed scheme. The proposed scheme affords good security, efficiency, and integrity and maintains anonymity. Full article
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