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Appl. Sci., Volume 6, Issue 2 (February 2016)

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Open AccessArticle
Investigations on the Cosputtered ITO-ZnO Transparent Electrode Ohmic Contacts to n-GaN
Appl. Sci. 2016, 6(2), 60; https://doi.org/10.3390/app6020060
Received: 29 December 2015 / Revised: 13 February 2016 / Accepted: 16 February 2016 / Published: 22 February 2016
Cited by 1 | Viewed by 2350 | PDF Full-text (1654 KB) | HTML Full-text | XML Full-text
Abstract
Transparent indium tin oxide (ITO) and cosputtered ITO-zinc oxide (ZnO) films’ contacts to an n-GaN epilayer were investigated. Both of these electrodes’ contact to the n-GaN epilayer showed Schottky behavior, although the contact resistance of the ITO-ZnO/n-GaN system was [...] Read more.
Transparent indium tin oxide (ITO) and cosputtered ITO-zinc oxide (ZnO) films’ contacts to an n-GaN epilayer were investigated. Both of these electrodes’ contact to the n-GaN epilayer showed Schottky behavior, although the contact resistance of the ITO-ZnO/n-GaN system was lower than that of the ITO/n-GaN system. By placing a thin Ti interlayer between the ITO-ZnO/n-GaN interface, nonalloyed ohmic contact was achieved. The inset Ti interlayer was both beneficial both for enhancing the outdiffusion of the nitrogen atoms at the surface of the n-GaN and suppressing the indiffusion of oxygen atoms from the surface of the ITO-ZnO to n-GaN. The figure-of-merit (FOM), evaluated from the specific contact resistance and optical property of the Ti/ITO-ZnO system’s contact to the n-GaN epilayer, was optimized further at an adequate thickness of the Ti interlayer. Full article
(This article belongs to the Special Issue Selected Papers from the 2015 International Conference on Inventions)
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Open AccessArticle
Atmospheric Pressure Plasma Surface Treatment of Rayon Flock Synthetic Leather with Tetramethylsilane
Appl. Sci. 2016, 6(2), 59; https://doi.org/10.3390/app6020059
Received: 11 December 2015 / Revised: 4 February 2016 / Accepted: 4 February 2016 / Published: 22 February 2016
Cited by 4 | Viewed by 2207 | PDF Full-text (5791 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates the use of atmospheric pressure plasma (APP) treatment for improving the surface hydrophobicity of rayon flock synthetic leather with organosilane precursor (tetramethylsilane (TMS)). Plasma deposition of TMS is regarded as an effective, simple, and low-pollution process. The results show that [...] Read more.
This paper investigates the use of atmospheric pressure plasma (APP) treatment for improving the surface hydrophobicity of rayon flock synthetic leather with organosilane precursor (tetramethylsilane (TMS)). Plasma deposition of TMS is regarded as an effective, simple, and low-pollution process. The results show that a highly hydrophobic surface is formulated on the rayon flock synthetic leather. Under a particular combination of treatment parameters, a hydrophobic surface was achieved on the APP-treated sample with a contact angle of 135° while the untreated sample had a contact angle of 0° (i.e., the fabric surface was completely drenched immediately). Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS) confirmed the deposition of organosilane. Full article
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Open AccessArticle
The Ultrasonic Polar Scan for Composite Characterization and Damage Assessment: Past, Present and Future
Appl. Sci. 2016, 6(2), 58; https://doi.org/10.3390/app6020058
Received: 30 December 2015 / Revised: 10 February 2016 / Accepted: 14 February 2016 / Published: 22 February 2016
Cited by 11 | Viewed by 1880 | PDF Full-text (3003 KB) | HTML Full-text | XML Full-text
Abstract
In the early 1980’s, the ultrasonic polar scan (UPS) technique was developed to assess the fiber direction of composites in a nondestructive way. In spite of the recognition by several researchers as being a sophisticated and promising methodology for nondestructive testing (NDT) and [...] Read more.
In the early 1980’s, the ultrasonic polar scan (UPS) technique was developed to assess the fiber direction of composites in a nondestructive way. In spite of the recognition by several researchers as being a sophisticated and promising methodology for nondestructive testing (NDT) and materials science, little advance was made during the following 30 years. Recently however, the UPS technique experienced a strong revival and various modifications to the original UPS setup have been successfully implemented. This revival has exposed several powerful capabilities and interesting applications of the UPS technique for material characterization and damage assessment. This paper gives a short historical overview of the UPS technique for characterizing and inspecting (damaged) fiber-reinforced plastics. In addition, a few future research lines are given, which will further expand the applicability and potential of the UPS method to a broader range of (damaged) materials, bringing the UPS technique to the next level of maturity. Full article
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Open AccessReview
A Review of Time-Scale Modification of Music Signals
Appl. Sci. 2016, 6(2), 57; https://doi.org/10.3390/app6020057
Received: 22 December 2015 / Revised: 22 January 2016 / Accepted: 25 January 2016 / Published: 18 February 2016
Cited by 9 | Viewed by 6495 | PDF Full-text (1618 KB) | HTML Full-text | XML Full-text
Abstract
Time-scale modification (TSM) is the task of speeding up or slowing down an audio signal’s playback speed without changing its pitch. In digital music production, TSM has become an indispensable tool, which is nowadays integrated in a wide range of music production software. [...] Read more.
Time-scale modification (TSM) is the task of speeding up or slowing down an audio signal’s playback speed without changing its pitch. In digital music production, TSM has become an indispensable tool, which is nowadays integrated in a wide range of music production software. Music signals are diverse—they comprise harmonic, percussive, and transient components, among others. Because of this wide range of acoustic and musical characteristics, there is no single TSM method that can cope with all kinds of audio signals equally well. Our main objective is to foster a better understanding of the capabilities and limitations of TSM procedures. To this end, we review fundamental TSM methods, discuss typical challenges, and indicate potential solutions that combine different strategies. In particular, we discuss a fusion approach that involves recent techniques for harmonic-percussive separation along with time-domain and frequency-domain TSM procedures. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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Open AccessArticle
Tailoring of Highly Intense THz Radiation Through High Brightness Electron Beams Longitudinal Manipulation
Appl. Sci. 2016, 6(2), 56; https://doi.org/10.3390/app6020056
Received: 4 November 2015 / Revised: 11 January 2016 / Accepted: 3 February 2016 / Published: 18 February 2016
Cited by 10 | Viewed by 1839 | PDF Full-text (2510 KB) | HTML Full-text | XML Full-text
Abstract
The ultra-short electron beams, produced through the velocity bunching compression technique at the SPARC_LAB test Facility (Frascati, Italy), are used to produce Coherent Transition Radiation in the terahertz (THz) range. This paper reports on the main features of this THz source, which have [...] Read more.
The ultra-short electron beams, produced through the velocity bunching compression technique at the SPARC_LAB test Facility (Frascati, Italy), are used to produce Coherent Transition Radiation in the terahertz (THz) range. This paper reports on the main features of this THz source, which have a spectral coverage up to 5 THz, a pulse duration down to 100 fs, and an energy per pulse on the order of tens of μJ. These figures of merits open the possibility to apply this source for nonlinear and THz pump-probe experiments in Solid-State Physics and material science. Full article
(This article belongs to the Special Issue Frontiers in Terahertz Science and Technology)
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Open AccessArticle
Icing Forecasting for Power Transmission Lines Based on a Wavelet Support Vector Machine Optimized by a Quantum Fireworks Algorithm
Appl. Sci. 2016, 6(2), 54; https://doi.org/10.3390/app6020054
Received: 22 December 2015 / Revised: 23 January 2016 / Accepted: 4 February 2016 / Published: 17 February 2016
Cited by 7 | Viewed by 1932 | PDF Full-text (4273 KB) | HTML Full-text | XML Full-text
Abstract
Icing on power transmission lines is a serious threat to the security and stability of the power grid, and it is necessary to establish a forecasting model to make accurate predictions of icing thickness. In order to improve the forecasting accuracy with regard [...] Read more.
Icing on power transmission lines is a serious threat to the security and stability of the power grid, and it is necessary to establish a forecasting model to make accurate predictions of icing thickness. In order to improve the forecasting accuracy with regard to icing thickness, this paper proposes a combination model based on a wavelet support vector machine (w-SVM) and a quantum fireworks algorithm (QFA) for prediction. First, this paper uses the wavelet kernel function to replace the Gaussian wavelet kernel function and improve the nonlinear mapping ability of the SVM. Second, the regular fireworks algorithm is improved by combining it with a quantum optimization algorithm to strengthen optimization performance. Lastly, the parameters of w-SVM are optimized using the QFA model, and the QFA-w-SVM icing thickness forecasting model is established. Through verification using real-world examples, the results show that the proposed method has a higher forecasting accuracy and the model is effective and feasible. Full article
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Open AccessArticle
Reallocating Charging Loads of Electric Vehicles in Distribution Networks
Appl. Sci. 2016, 6(2), 53; https://doi.org/10.3390/app6020053
Received: 21 December 2015 / Revised: 22 January 2016 / Accepted: 6 February 2016 / Published: 16 February 2016
Cited by 1 | Viewed by 2144 | PDF Full-text (13015 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the charging loads of electric vehicles were controlled to avoid their impact on distribution networks. A centralized control algorithm was developed using unbalanced optimal power flow calculations with a time resolution of one minute. The charging loads were optimally reallocated [...] Read more.
In this paper, the charging loads of electric vehicles were controlled to avoid their impact on distribution networks. A centralized control algorithm was developed using unbalanced optimal power flow calculations with a time resolution of one minute. The charging loads were optimally reallocated using a central controller based on non-linear programming. Electric vehicles were recharged using the proposed control algorithm considering the network constraints of voltage magnitudes, voltage unbalances, and limitations of the network components (transformers and cables). Simulation results showed that network components at the medium voltage level can tolerate high uptakes of uncontrolled recharged electric vehicles. However, at the low voltage level, network components exceeded their limits with these high uptakes of uncontrolled charging loads. Using the proposed centralized control algorithm, these high uptakes of electric vehicles were accommodated in the network under study without the need of upgrading the network components. Full article
(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)
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Open AccessArticle
Adaptive Control of Active Magnetic Bearing against Milling Dynamics
Appl. Sci. 2016, 6(2), 52; https://doi.org/10.3390/app6020052
Received: 27 November 2015 / Revised: 8 January 2016 / Accepted: 28 January 2016 / Published: 15 February 2016
Cited by 3 | Viewed by 2357 | PDF Full-text (8394 KB) | HTML Full-text | XML Full-text
Abstract
For improving the defects in milling processes caused by traditional spindle bearings, e.g., the dimensional discrepancy of a finished workpiece due to bearing wear or oil pollution by lubricant, a novel embedded cylindrical-array magnetic actuator (ECAMA) is designed for milling applications. Since ECAMA [...] Read more.
For improving the defects in milling processes caused by traditional spindle bearings, e.g., the dimensional discrepancy of a finished workpiece due to bearing wear or oil pollution by lubricant, a novel embedded cylindrical-array magnetic actuator (ECAMA) is designed for milling applications. Since ECAMA is a non-contact type actuator, a control strategy named fuzzy model-reference adaptive control (FMRAC) is synthesized to account for the nonlinearities of milling dynamics and magnetic force. In order to ensure the superior performance of spindle position regulation, the employed models in FMRAC are all constructed by experiments. Based on the experimental results, the magnetic force by ECAMA is much stronger than that by the traditional active magnetic bearing (AMB) design under the same test conditions and identical overall size. The efficacy of ECAMA to suppress the spindle position deviation with the aid of FMRAC has been verified as well via numerical simulations and practical metal cutting. Full article
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Open AccessReview
Dynamics of Carrier Transport in Nanoscale Materials: Origin of Non-Drude Behavior in the Terahertz Frequency Range
Appl. Sci. 2016, 6(2), 50; https://doi.org/10.3390/app6020050
Received: 18 November 2015 / Accepted: 27 January 2016 / Published: 14 February 2016
Cited by 2 | Viewed by 1649 | PDF Full-text (1820 KB) | HTML Full-text | XML Full-text
Abstract
It is known that deviation from the Drude law for free carriers is dramatic in most electronically conductive nanomaterials. We review recent studies of the conductivity of nanoscale materials at terahertz (THz) frequencies. We suggest that among a variety of theoretical formalisms, a [...] Read more.
It is known that deviation from the Drude law for free carriers is dramatic in most electronically conductive nanomaterials. We review recent studies of the conductivity of nanoscale materials at terahertz (THz) frequencies. We suggest that among a variety of theoretical formalisms, a model of series sequence of transport involving grains and grain boundaries provides a reasonable explanation of Lorentz-type resonance (non-Drude behavior) in nanomaterials. Of particular interest is why do free carriers exhibit a Lorentz-type resonance. Full article
(This article belongs to the Special Issue Frontiers in Terahertz Science and Technology)
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Open AccessArticle
Dynamic Characterization of Cohesive Material Based on Wave Velocity Measurements
Appl. Sci. 2016, 6(2), 49; https://doi.org/10.3390/app6020049
Received: 29 October 2015 / Revised: 14 January 2016 / Accepted: 15 January 2016 / Published: 9 February 2016
Cited by 8 | Viewed by 1905 | PDF Full-text (6859 KB) | HTML Full-text | XML Full-text
Abstract
The paper presents a description of the dynamic properties of cohesive material, namely silty clays, obtained by using one of the applied seismology methods, the bender elements technique. The authors’ aim was to present the dynamics of a porous medium, in particular an [...] Read more.
The paper presents a description of the dynamic properties of cohesive material, namely silty clays, obtained by using one of the applied seismology methods, the bender elements technique. The authors’ aim was to present the dynamics of a porous medium, in particular an extremely important passage of seismic waves that travel through the bulk of a medium. Nowadays, the application of the bender element (BE) technique to measure, e.g., small strain shear stiffness of soils in the laboratory is well recognized, since it allows for reliable and relatively economical shear wave velocity measurements during various laboratory experiments. However, the accurate estimation of arrival time during BE tests is in many cases unclear. Two different interpretation procedures (from the time domain) of BE tests in order to measure travel times of waves were examined. Those values were then used to calculate shear and compression wave velocities and elastic moduli. Results showed that the dynamic parameters obtained by the start-to-start method were always slightly larger (up to about 20%) than those obtained using the peak-to-peak one. It was found that the peak-to-peak method led to more scattered results in comparison to the start-to-start method. Moreover, the influence of the excitation frequency, the mean effective stress and the unloading process on the dynamic properties of the tested material was studied. In addition, the obtained results highlighted the importance of initial signal frequency and the necessity to choose an appropriate range of frequencies to measure the shear wave velocity in clayey soils. Full article
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Open AccessArticle
Method for Analysis of an Offshore Heave Compensator
Appl. Sci. 2016, 6(2), 51; https://doi.org/10.3390/app6020051
Received: 30 November 2015 / Revised: 29 January 2016 / Accepted: 2 February 2016 / Published: 8 February 2016
Cited by 1 | Viewed by 2149 | PDF Full-text (4647 KB) | HTML Full-text | XML Full-text
Abstract
A heave compensation system consists of a drill string compensator (DSC) and an active heave compensator (AHC) cylinder, which together produce control force over an oil pressure system suitable for transmission of considerable power and compensating for heaving motion of the hull during [...] Read more.
A heave compensation system consists of a drill string compensator (DSC) and an active heave compensator (AHC) cylinder, which together produce control force over an oil pressure system suitable for transmission of considerable power and compensating for heaving motion of the hull during drilling work. In this study, a heave compensator of an oil pressure system was simulated to draw a conclusion, which was verified by comparison with the result of a test conducted using an actual miniature model. The compensation rate was 95%, based on which the dynamic behaviors of an actual-size heave compensator were presumed. Furthermore, the speed of each cylinder and the acceleration of heave can be determined and used to fabricate an actual-size heave compensator. Full article
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Open AccessArticle
Current Market Demand for Core Competencies of Librarianship—A Text Mining Study of American Library Association’s Advertisements from 2009 through 2014
Appl. Sci. 2016, 6(2), 48; https://doi.org/10.3390/app6020048
Received: 27 October 2015 / Revised: 14 January 2016 / Accepted: 26 January 2016 / Published: 8 February 2016
Cited by 5 | Viewed by 2084 | PDF Full-text (615 KB) | HTML Full-text | XML Full-text
Abstract
As librarianship evolves, it is important to examine the changes that have taken place in professional requirements. To provide an understanding of the current market demand for core competencies of librarianship, this article conducts a semi-automatic methodology to analyze job advertisements (ads) posted [...] Read more.
As librarianship evolves, it is important to examine the changes that have taken place in professional requirements. To provide an understanding of the current market demand for core competencies of librarianship, this article conducts a semi-automatic methodology to analyze job advertisements (ads) posted on the American Library Association (ALA) Joblist from 2009 through 2014. There is evidence that the ability to solve unexpected complex problems and to provide superior customer service gained increasing importance for librarians during those years. The authors contend that the findings in this report question the status quo of core competencies of librarianship in the US job market. Full article
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Open AccessArticle
Vehicle Speed Estimation and Forecasting Methods Based on Cellular Floating Vehicle Data
Appl. Sci. 2016, 6(2), 47; https://doi.org/10.3390/app6020047
Received: 9 November 2015 / Revised: 16 January 2016 / Accepted: 25 January 2016 / Published: 5 February 2016
Cited by 7 | Viewed by 2417 | PDF Full-text (2149 KB) | HTML Full-text | XML Full-text
Abstract
Traffic information estimation and forecasting methods based on cellular floating vehicle data (CFVD) are proposed to analyze the signals (e.g., handovers (HOs), call arrivals (CAs), normal location updates (NLUs) and periodic location updates (PLUs)) from cellular networks. For traffic information estimation, analytic models [...] Read more.
Traffic information estimation and forecasting methods based on cellular floating vehicle data (CFVD) are proposed to analyze the signals (e.g., handovers (HOs), call arrivals (CAs), normal location updates (NLUs) and periodic location updates (PLUs)) from cellular networks. For traffic information estimation, analytic models are proposed to estimate the traffic flow in accordance with the amounts of HOs and NLUs and to estimate the traffic density in accordance with the amounts of CAs and PLUs. Then, the vehicle speeds can be estimated in accordance with the estimated traffic flows and estimated traffic densities. For vehicle speed forecasting, a back-propagation neural network algorithm is considered to predict the future vehicle speed in accordance with the current traffic information (i.e., the estimated vehicle speeds from CFVD). In the experimental environment, this study adopted the practical traffic information (i.e., traffic flow and vehicle speed) from Taiwan Area National Freeway Bureau as the input characteristics of the traffic simulation program and referred to the mobile station (MS) communication behaviors from Chunghwa Telecom to simulate the traffic information and communication records. The experimental results illustrated that the average accuracy of the vehicle speed forecasting method is 95.72%. Therefore, the proposed methods based on CFVD are suitable for an intelligent transportation system. Full article
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Open AccessArticle
Biomedical Applications of Antibacterial Nanofiber Mats Made of Electrospinning with Wire Electrodes
Appl. Sci. 2016, 6(2), 46; https://doi.org/10.3390/app6020046
Received: 12 December 2015 / Revised: 22 January 2016 / Accepted: 28 January 2016 / Published: 4 February 2016
Cited by 9 | Viewed by 1874 | PDF Full-text (4270 KB) | HTML Full-text | XML Full-text
Abstract
Twisted stainless steel wires are used as wire electrodes for electrospinning the polyvinyl alcohol (PVA)/zinc citrate nanofiber mats. The morphology and diameter of the nanofibers in PVA/zinc citrate nanofiber mats are evaluated. We measured the antibacterial efficacy against Staphylococcus aureus (S. aureus [...] Read more.
Twisted stainless steel wires are used as wire electrodes for electrospinning the polyvinyl alcohol (PVA)/zinc citrate nanofiber mats. The morphology and diameter of the nanofibers in PVA/zinc citrate nanofiber mats are evaluated. We measured the antibacterial efficacy against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) of the nanofiber mats. We also examined the cell adhesion affinity of mammalian tissue culture cells on these nanofiber mats. Our results indicate that an increase in zinc citrate increases the viscosity and electrical conductivity of PVA solution. In addition, increasing zinc citrate results in a smaller diameter of nanofibers that reaches below 100 nm. According to the antibacterial test results, increasing zinc citrate enlarges the inhibition zone of S. aureus but only has a bacteriostatic effect against E. coli. Finally, cell adhesion test results indicate that all nanofiber mats have satisfactory cell attachment regardless of the content of zinc citrate. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessArticle
Wavelet Packet Decomposition to Characterize Injection Molding Tool Damage
Appl. Sci. 2016, 6(2), 45; https://doi.org/10.3390/app6020045
Received: 2 December 2015 / Revised: 7 January 2016 / Accepted: 19 January 2016 / Published: 4 February 2016
Cited by 2 | Viewed by 1886 | PDF Full-text (3412 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents measurements of acoustic emission (AE) signals during the injection molding of polypropylene with new and damaged mold. The damaged injection mold has cracks induced by laser surface heat treatment. Standard test specimens were injection molded, commonly used for examining the [...] Read more.
This paper presents measurements of acoustic emission (AE) signals during the injection molding of polypropylene with new and damaged mold. The damaged injection mold has cracks induced by laser surface heat treatment. Standard test specimens were injection molded, commonly used for examining the shrinkage behavior of various thermoplastic materials. The measured AE burst signals during injection molding cycle are presented. For injection molding tool integrity prediction, different AE burst signals’ descriptors are defined. To lower computational complexity and increase performance, the feature selection method was implemented to define a feature subset in an appropriate multidimensional space to characterize the integrity of the injection molding tool and the injection molding process steps. The feature subset was used for neural network pattern recognition of AE signals during the full time of the injection molding cycle. The results confirm that acoustic emission measurement during injection molding of polymer materials is a promising technique for characterizing the integrity of molds with respect to damage, even with resonant sensors. Full article
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Open AccessArticle
Web3DGIS-Based System for Reservoir Landslide Monitoring and Early Warning
Appl. Sci. 2016, 6(2), 44; https://doi.org/10.3390/app6020044
Received: 6 November 2015 / Revised: 13 January 2016 / Accepted: 26 January 2016 / Published: 4 February 2016
Cited by 5 | Viewed by 1961 | PDF Full-text (2387 KB) | HTML Full-text | XML Full-text
Abstract
Landslides are the most frequent type of natural disaster, and they bring about large-scale damage and are a threat to human lives and infrastructure; therefore, the ability to conduct real-time monitoring and early warning is important. In this study, a Web3DGIS (Web3D geographic [...] Read more.
Landslides are the most frequent type of natural disaster, and they bring about large-scale damage and are a threat to human lives and infrastructure; therefore, the ability to conduct real-time monitoring and early warning is important. In this study, a Web3DGIS (Web3D geographic information systems) system for monitoring and forecasting landslides was developed using the Danjiangkou Reservoir area as a case study. The development of this technique involved system construction, functional design, organizing and managing multi-source spatial data, and implementing a forecasting plan and landslide-forecasting model. By integrating sensor technologies, spatial information technologies, 3D visualization technologies, and a landslide-forecasting model, the results of this study provide a tool for real-time monitoring at potential landslide sites. When relevant data from these sites reach threshold values, the model automatically initiates forecasting procedures, and sends information to disaster prevention sectors for emergency management. Full article
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Open AccessArticle
Identification of a Critical Time with Acoustic Emission Monitoring during Static Fatigue Tests on Ceramic Matrix Composites: Towards Lifetime Prediction
Appl. Sci. 2016, 6(2), 43; https://doi.org/10.3390/app6020043
Received: 15 December 2015 / Revised: 19 January 2016 / Accepted: 21 January 2016 / Published: 3 February 2016
Cited by 4 | Viewed by 1679 | PDF Full-text (4404 KB) | HTML Full-text | XML Full-text
Abstract
Non-oxide fiber-reinforced ceramic-matrix composites are promising candidates for some aeronautic applications that require good thermomechanical behavior over long periods of time. This study focuses on the behavior of a SiCf/[Si-B-C] composite with a self-healing matrix at intermediate temperature under air. Static [...] Read more.
Non-oxide fiber-reinforced ceramic-matrix composites are promising candidates for some aeronautic applications that require good thermomechanical behavior over long periods of time. This study focuses on the behavior of a SiCf/[Si-B-C] composite with a self-healing matrix at intermediate temperature under air. Static fatigue experiments were performed below 600 °C and a lifetime diagram is presented. Damage is monitored both by strain measurement and acoustic emission during the static fatigue experiments. Two methods of real-time analysis of associated energy release have been developed. They allow for the identification of a characteristic time that was found to be close to 55% of the measured rupture time. This critical time reflects a critical local energy release assessed by the applicability of the Benioff law. This critical aspect is linked to a damage phase where slow crack growth in fibers is prevailing leading to ultimate fracture of the composite. Full article
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Open AccessArticle
Design of an Image-Servo Mask Alignment System Using Dual CCDs with an XXY Stage
Appl. Sci. 2016, 6(2), 42; https://doi.org/10.3390/app6020042
Received: 9 October 2015 / Revised: 8 January 2016 / Accepted: 21 January 2016 / Published: 2 February 2016
Cited by 2 | Viewed by 2272 | PDF Full-text (4095 KB) | HTML Full-text | XML Full-text
Abstract
Mask alignment of photolithography technology is used in many applications, such as micro electro mechanical systems’ semiconductor process, printed circuits board, and flat panel display. As the dimensions of the product are getting smaller and smaller, the automatic mask alignment of photolithography is [...] Read more.
Mask alignment of photolithography technology is used in many applications, such as micro electro mechanical systems’ semiconductor process, printed circuits board, and flat panel display. As the dimensions of the product are getting smaller and smaller, the automatic mask alignment of photolithography is becoming more and more important. The traditional stacked XY-Θz stage is heavy and it has cumulative flatness errors due to its stacked assembly mechanism. The XXY stage has smaller cumulative error due to its coplanar design and it can move faster than the traditional XY-Θz stage. However, the relationship between the XXY stage’s movement and the commands of the three motors is difficult to compute, because the movements of the three motors on the same plane are coupling. Therefore, an artificial neural network is studied to establish a nonlinear mapping from the desired position and orientation of the stage to three motors’ commands. Further, this paper proposes an image-servo automatic mask alignment system, which consists of a coplanar XXY stage, dual GIGA-E CCDs with lens and a programmable automatic controller (PAC). Before preforming the compensation, a self-developed visual-servo provides the positioning information which is obtained from the image processing and pattern recognition according to the specified fiducial marks. To obtain better precision, two methods including the center of gravity method and the generalize Hough Transformation are studied to correct the shift positioning error. Full article
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Open AccessArticle
Implementation of FPGA-Based Charge Control for a Self-Sufficient Solar Tracking Power Supply System
Appl. Sci. 2016, 6(2), 41; https://doi.org/10.3390/app6020041
Received: 6 December 2015 / Revised: 16 January 2016 / Accepted: 19 January 2016 / Published: 2 February 2016
Cited by 8 | Viewed by 2299 | PDF Full-text (3230 KB) | HTML Full-text | XML Full-text
Abstract
This study used a field-programmable gate array (FPGA) with a Xilinx Spartan-3 FPGA to implement Reflex charge control in a dual-axis solar tracking system with maximum power point tracking (MPPT). The chaos embedded particle swarm optimization method was used to search for the [...] Read more.
This study used a field-programmable gate array (FPGA) with a Xilinx Spartan-3 FPGA to implement Reflex charge control in a dual-axis solar tracking system with maximum power point tracking (MPPT). The chaos embedded particle swarm optimization method was used to search for the optimum gain constants of the PI controller and the Reflex charging frequency. This scheme not only increases the output power of solar panels but also has a significant effect on switching loss and oscillation of solar charging. The experiment results showed that the proposed method can also significantly improve temperature rise, and that charging efficiency is also better than it is in a traditional charge mode. The results also showed that charging power was enough for solar tracking and the requirements of the charging system. The most significant contribution of this paper is that the scheme can be applied to any active solar tracking and charging system. Full article
(This article belongs to the Special Issue Selected Papers from the 2015 International Conference on Inventions)
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Open AccessArticle
A Microfluidic Device for Hydrodynamic Trapping and Manipulation Platform of a Single Biological Cell
Appl. Sci. 2016, 6(2), 40; https://doi.org/10.3390/app6020040
Received: 17 November 2015 / Revised: 16 December 2015 / Accepted: 5 January 2016 / Published: 1 February 2016
Cited by 7 | Viewed by 2288 | PDF Full-text (5523 KB) | HTML Full-text | XML Full-text
Abstract
To perform specific analysis for the single cell, individual cells have to be captured and separated from each other before further treatments and analysis can be carried out. This paper presents the design, simulation, fabrication, and testing of a microfluidic device for trapping [...] Read more.
To perform specific analysis for the single cell, individual cells have to be captured and separated from each other before further treatments and analysis can be carried out. This paper presents the design, simulation, fabrication, and testing of a microfluidic device for trapping a single cell/particle based on a hydrodynamic technique. A T-channel trapping chip has been proposed to provide single-cell trapping and consequently could be a platform for cell treatments and manipulations. A finite element T-channel trapping model was developed using Abaqus FEA™ software to observe it’s trapping ability by optimizing the channel’s geometry and RhMain/RhTrap ratio. A proof of concept demonstration for cell trapping in the T-channel model was presented in the simulation analysis and experimental work using HUVEC cell aggregate. The T-channel was found to be able to trap a single cell via the hydrodynamic trapping concept using an appropriate channel geometry and RhMain/RhTrap ratio. The proposed T-channel single-cell trapping has potential application for single cell characterization and single 3D cell aggregates treatments and analysis. Full article
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Open AccessArticle
Frequency-Dependent Amplitude Panning for the Stereophonic Image Enhancement of Audio Recorded Using Two Closely Spaced Microphones
Appl. Sci. 2016, 6(2), 39; https://doi.org/10.3390/app6020039
Received: 19 November 2015 / Revised: 19 January 2016 / Accepted: 21 January 2016 / Published: 1 February 2016
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Abstract
In this paper, we propose a new frequency-dependent amplitude panning method for stereophonic image enhancement applied to a sound source recorded using two closely spaced omni-directional microphones. The ability to detect the direction of such a sound source is limited due to weak [...] Read more.
In this paper, we propose a new frequency-dependent amplitude panning method for stereophonic image enhancement applied to a sound source recorded using two closely spaced omni-directional microphones. The ability to detect the direction of such a sound source is limited due to weak spatial information, such as the inter-channel time difference (ICTD) and inter-channel level difference (ICLD). Moreover, when sound sources are recorded in a convolutive or a real room environment, the detection of sources is affected by reverberation effects. Thus, the proposed method first tries to estimate the source direction depending on the frequency using azimuth-frequency analysis. Then, a frequency-dependent amplitude panning technique is proposed to enhance the stereophonic image by modifying the stereophonic law of sines. To demonstrate the effectiveness of the proposed method, we compare its performance with that of a conventional method based on the beamforming technique in terms of directivity pattern, perceived direction, and quality degradation under three different recording conditions (anechoic, convolutive, and real reverberant). The comparison shows that the proposed method gives us better stereophonic images in a stereo loudspeaker reproduction than the conventional method without any annoying effects. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
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Open AccessArticle
A Novel Bearing Lubricating Device Based on the Piezoelectric Micro-Jet
Appl. Sci. 2016, 6(2), 38; https://doi.org/10.3390/app6020038
Received: 15 December 2015 / Revised: 21 January 2016 / Accepted: 21 January 2016 / Published: 1 February 2016
Cited by 9 | Viewed by 1987 | PDF Full-text (6867 KB) | HTML Full-text | XML Full-text
Abstract
A novel bearing lubricating device, which is embedded in gyroscope’s bearing system and based on the theory of the piezoelectric micro-jet, was designed for this study. The embedded structure of a bearing lubricating system can make effective use of the limited space of [...] Read more.
A novel bearing lubricating device, which is embedded in gyroscope’s bearing system and based on the theory of the piezoelectric micro-jet, was designed for this study. The embedded structure of a bearing lubricating system can make effective use of the limited space of bearing systems without increasing the whole mass of the system. The drop-on-demand (DOD) lubrication can be realized by the piezoelectric micro-jet system to implement the long acting lubrication of the bearing system. A mathematical model of inlet boundary conditions was established to carry on the numerical simulation based on CFD. The motion states of the droplets with different voltage excitations were analyzed via numerical simulations, and the injection performances of the piezoelectric micro-jet lubricating device were tested in accordance with past experiments. The influences of different parameters of voltage excitation on injection performance were obtained, and the methods of adjusting the injection performance to meet different requirements are given according to the analyses of the results. The mathematical model and numerical simulation method were confirmed by comparing the results of past simulations and experiments. Full article
(This article belongs to the Special Issue Ferroelectric Ceramics)
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Open AccessArticle
Distributed Global Function Model Finding for Wireless Sensor Network Data
Appl. Sci. 2016, 6(2), 37; https://doi.org/10.3390/app6020037
Received: 7 December 2015 / Revised: 12 January 2016 / Accepted: 15 January 2016 / Published: 28 January 2016
Cited by 2 | Viewed by 1304 | PDF Full-text (5062 KB) | HTML Full-text | XML Full-text
Abstract
Function model finding has become an important tool for analysis of data collected from wireless sensor networks (WSNs). With the development of WSNs, a large number of sensors have been widely deployed so that the collected data show the characteristics of distribution and [...] Read more.
Function model finding has become an important tool for analysis of data collected from wireless sensor networks (WSNs). With the development of WSNs, a large number of sensors have been widely deployed so that the collected data show the characteristics of distribution and mass. For distributed and massive sensor data, traditional centralized function model finding algorithms would lead to a significant decrease in performance. To solve this problem, this paper proposes a distributed global function model finding algorithm for wireless sensor network data (DGFMF-WSND). In DGFMF-WSND, on the basis of gene expression programming (GEP), an adaptive population generation strategy based on sub-population associated evolution is applied to improve the convergence speed of GEP. Secondly, to solve the generation of global function model in distributed wireless sensor networks data, this paper provides a global model generation algorithm based on unconstrained nonlinear least squares. Four representative datasets are used to evaluate the performance of the proposed algorithm. The comparative results show that the improved GEP with adaptive population generation strategy outperforms all other algorithms on the average convergence speed, time-consumption, value of R-square, and prediction accuracy. Meanwhile, experimental results also show that DGFMF-WSND has a clear advantage in terms of time-consumption and error of fitting. Moreover, with increasing of dataset size, DGFMF-WSND also demonstrates good speed-up ratio and scale-up ratio. Full article
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Open AccessArticle
Parallel Dynamic Analysis of a Large-Scale Water Conveyance Tunnel under Seismic Excitation Using ALE Finite-Element Method
Appl. Sci. 2016, 6(2), 36; https://doi.org/10.3390/app6020036
Received: 15 December 2015 / Revised: 21 January 2016 / Accepted: 22 January 2016 / Published: 28 January 2016
Cited by 2 | Viewed by 2174 | PDF Full-text (9886 KB) | HTML Full-text | XML Full-text
Abstract
Parallel analyses about the dynamic responses of a large-scale water conveyance tunnel under seismic excitation are presented in this paper. A full three-dimensional numerical model considering the water-tunnel-soil coupling is established and adopted to investigate the tunnel’s dynamic responses. The movement and sloshing [...] Read more.
Parallel analyses about the dynamic responses of a large-scale water conveyance tunnel under seismic excitation are presented in this paper. A full three-dimensional numerical model considering the water-tunnel-soil coupling is established and adopted to investigate the tunnel’s dynamic responses. The movement and sloshing of the internal water are simulated using the multi-material Arbitrary Lagrangian Eulerian (ALE) method. Nonlinear fluid–structure interaction (FSI) between tunnel and inner water is treated by using the penalty method. Nonlinear soil-structure interaction (SSI) between soil and tunnel is dealt with by using the surface to surface contact algorithm. To overcome computing power limitations and to deal with such a large-scale calculation, a parallel algorithm based on the modified recursive coordinate bisection (MRCB) considering the balance of SSI and FSI loads is proposed and used. The whole simulation is accomplished on Dawning 5000 A using the proposed MRCB based parallel algorithm optimized to run on supercomputers. The simulation model and the proposed approaches are validated by comparison with the added mass method. Dynamic responses of the tunnel are analyzed and the parallelism is discussed. Besides, factors affecting the dynamic responses are investigated. Better speedup and parallel efficiency show the scalability of the parallel method and the analysis results can be used to aid in the design of water conveyance tunnels. Full article
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Open AccessArticle
Detection of On-Chip Generated Weak Microwave Radiation Using Superconducting Normal-Metal SET
Appl. Sci. 2016, 6(2), 35; https://doi.org/10.3390/app6020035
Received: 30 November 2015 / Revised: 13 January 2016 / Accepted: 19 January 2016 / Published: 27 January 2016
Cited by 4 | Viewed by 2169 | PDF Full-text (9631 KB) | HTML Full-text | XML Full-text
Abstract
The present work addresses quantum interaction phenomena of microwave radiation with a single-electron tunneling system. For this study, an integrated circuit is implemented, combining on the same chip a Josephson junction (Al/AlO x /Al) oscillator and a single-electron transistor (SET) with the superconducting [...] Read more.
The present work addresses quantum interaction phenomena of microwave radiation with a single-electron tunneling system. For this study, an integrated circuit is implemented, combining on the same chip a Josephson junction (Al/AlO x /Al) oscillator and a single-electron transistor (SET) with the superconducting island (Al) and normal-conducting leads (AuPd). The transistor is demonstrated to operate as a very sensitive photon detector, sensing down to a few tens of photons per second in the microwave frequency range around f ∼ 100 GHz. On the other hand, the Josephson oscillator, realized as a two-junction SQUID and coupled to the detector via a coplanar transmission line (Al), is shown to provide a tunable source of microwave radiation: controllable variations in power or in frequency were accompanied by significant changes in the detector output, when applying magnetic flux or adjusting the voltage across the SQUID, respectively. It was also shown that the effect of substrate-mediated phonons, generated by our microwave source, on the detector output was negligibly small. Full article
(This article belongs to the Special Issue Applied Single-Electron Transistors)
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Open AccessArticle
A Microwave-Assisted Simultaneous Distillation and Extraction Method for the Separation of Polysaccharides and Essential Oil from the Leaves of Taxus chinensis Var. mairei
Appl. Sci. 2016, 6(2), 19; https://doi.org/10.3390/app6020019
Received: 6 October 2015 / Revised: 7 January 2016 / Accepted: 8 January 2016 / Published: 27 January 2016
Cited by 3 | Viewed by 3420 | PDF Full-text (2241 KB) | HTML Full-text | XML Full-text
Abstract
An efficient microwave-assisted simultaneous distillation and extraction (MA-SDE) method has been developed for the separation of polysaccharides and essential oil from Taxus chinensis var. mairei. The key operating parameters for MA-SDE were optimized by single factor and central composite design experiments, and [...] Read more.
An efficient microwave-assisted simultaneous distillation and extraction (MA-SDE) method has been developed for the separation of polysaccharides and essential oil from Taxus chinensis var. mairei. The key operating parameters for MA-SDE were optimized by single factor and central composite design experiments, and the optimal conditions were found to include a particle size of 60–80 mesh, liquid/solid ratio of 22.5 mL/g, extraction time of 17.5 min, microwave power of 547 W, and dichloromethane was used as the extraction solvent of the essential oil. The yields obtained for polysaccharides and essential oil under the optimized conditions were 6.39% ± 0.12% and 0.27% ± 0.03%, respectively. The MA-SDE method was also compared with conventional heat reflux extraction (HRE) and hydrodistillation extraction (HDE). The MA-SDE method not only allowed for the simultaneous extraction of polysaccharides and essential oil, but also completed the task with a much shorter extraction time of 17.5 min (HRE and HDE required 3 and 6 h, respectively). Furthermore, the MA-SDE method gave increased extraction yields for polysaccharides (1.14-fold higher than HRE) and essential oil (1.23-fold higher than HDE). Based on these results, this MA-SDE method represents a rapid and efficient technique for the simultaneous extraction of polysaccharides and essential oil. Full article
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Open AccessArticle
A Physically—Based Geometry Model for Transport Distance Estimation of Rainfall-Eroded Soil Sediment
Appl. Sci. 2016, 6(2), 34; https://doi.org/10.3390/app6020034
Received: 28 October 2015 / Revised: 14 January 2016 / Accepted: 19 January 2016 / Published: 25 January 2016
Cited by 2 | Viewed by 1477 | PDF Full-text (6377 KB) | HTML Full-text | XML Full-text
Abstract
Estimations of rainfall-induced soil erosion are mostly derived from the weight of sediment measured in natural runoff. The transport distance of eroded soil is important for evaluating landscape evolution but is difficult to estimate, mainly because it cannot be linked directly to the [...] Read more.
Estimations of rainfall-induced soil erosion are mostly derived from the weight of sediment measured in natural runoff. The transport distance of eroded soil is important for evaluating landscape evolution but is difficult to estimate, mainly because it cannot be linked directly to the eroded sediment weight. The volume of eroded soil is easier to calculate visually using popular imaging tools, which can aid in estimating the transport distance of eroded soil through geometry relationships. In this study, we present a straightforward geometry model to predict the maximum sediment transport distance incurred by rainfall events of various intensity and duration. In order to verify our geometry prediction model, a series of experiments are reported in the form of a sediment volume. The results show that cumulative rainfall has a linear relationship with the total volume of eroded soil. The geometry model can accurately estimate the maximum transport distance of eroded soil by cumulative rainfall, with a low root-mean-square error (4.7–4.8) and a strong linear correlation (0.74–0.86). Full article
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Open AccessArticle
Proof of Concept of Crack Localization Using Negative Pressure Waves in Closed Tubes for Later Application in Effective SHM System for Additive Manufactured Components
Appl. Sci. 2016, 6(2), 33; https://doi.org/10.3390/app6020033
Received: 17 November 2015 / Revised: 14 January 2016 / Accepted: 18 January 2016 / Published: 25 January 2016
Cited by 1 | Viewed by 1658 | PDF Full-text (7259 KB) | HTML Full-text | XML Full-text
Abstract
Additive manufactured components have a different metallurgic structure and are more prone to fatigue cracks than conventionally produced metals. In earlier papers, an effective Structural Health Monitoring solution was presented to detect fatigue cracks in additive manufactured components. Small subsurface capillaries are embedded [...] Read more.
Additive manufactured components have a different metallurgic structure and are more prone to fatigue cracks than conventionally produced metals. In earlier papers, an effective Structural Health Monitoring solution was presented to detect fatigue cracks in additive manufactured components. Small subsurface capillaries are embedded in the structure and pressurized (vacuum or overpressure). A crack that initiated at the component’s surface will propagate towards the capillary and finally breach it. One capillary suffices to inspect a large area of the component, which makes it interesting to locate the crack on the basis of the pressure measurements. Negative pressure waves (NPW) arise from the abrupt encounter of high pressure fluid with low pressure fluid and can serve as a basis to locate the crack. A test set-up with a controllable leak valve was built to investigate the feasibility of using NPW to localize a leak in closed tubes with small lengths. Reflections are expected to occur at the ends of the tube, possibly limiting the localization accuracy. In this paper, the results of the tests on the test set-up are reported. It will be shown that the crack could be localized with high accuracy (millimeter accuracy) which proves the concept of crack localization on basis of NPW in a closed tube of small length. Full article
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Open AccessArticle
Research on a Composite Power-Superimposed Ultrasonic Vibrator for Wire Drawing
Appl. Sci. 2016, 6(2), 32; https://doi.org/10.3390/app6020032
Received: 28 October 2015 / Revised: 12 January 2016 / Accepted: 15 January 2016 / Published: 25 January 2016
Cited by 1 | Viewed by 1966 | PDF Full-text (5210 KB) | HTML Full-text | XML Full-text
Abstract
Vibration power and amplitude are essential factors in ultrasonic drawing processes, especially for difficult-to-draw materials like titanium and its alloys. This paper presents a new composite power-superimposed ultrasonic vibrator for wire drawing which was driven by three separate ultrasonic transducers. The transducers were [...] Read more.
Vibration power and amplitude are essential factors in ultrasonic drawing processes, especially for difficult-to-draw materials like titanium and its alloys. This paper presents a new composite power-superimposed ultrasonic vibrator for wire drawing which was driven by three separate ultrasonic transducers. The transducers were uniformly distributed around the circular cross section of the vibrator, with their axes along the radial direction and pointing to the center. The vibrator can concentrate the vibrational energy of multiple transducers and transform the radial vibration into a longitudinal vibrator because of the Poisson effect and therefore output larger vibration power and amplitude. In the paper, the four-terminal network method was used to establish the vibration equations of the vibrator. The FE model was established in ANSYS to investigate its characteristics under various excitation conditions. A prototype was manufactured and measurements were performed to verify the validation of FEA results. The results matched well with the theoretical results. It was found that the composite vibrator achieved an amplitude of about 40 μm when driven by square wave signals with 120° in phase difference, which implies a potential way of applying ultrasonic vibration to the processing of difficult-to-draw materials. Full article
(This article belongs to the Special Issue Ferroelectric Ceramics)
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Open AccessArticle
Phosphorus Distribution in Soils from Australian Dairy and Beef Rearing Pastoral Systems
Appl. Sci. 2016, 6(2), 31; https://doi.org/10.3390/app6020031
Received: 14 November 2015 / Revised: 29 December 2015 / Accepted: 15 January 2016 / Published: 25 January 2016
Cited by 1 | Viewed by 1551 | PDF Full-text (1254 KB) | HTML Full-text | XML Full-text
Abstract
The influence of soil type and management practices on P distribution in soils from Australian dairy and beef rearing pastoral systems has been investigated by chemical measurements and phosphorus-31 (31P) nuclear magnetic resonance (NMR) spectroscopy. The amount and forms of P [...] Read more.
The influence of soil type and management practices on P distribution in soils from Australian dairy and beef rearing pastoral systems has been investigated by chemical measurements and phosphorus-31 (31P) nuclear magnetic resonance (NMR) spectroscopy. The amount and forms of P within the soil profile varied with soil type, with the acidic red Ferrosols containing relatively high orthophosphate concentrations, averaging 72.2% compared with 66.8% for Dermosols, under similar management conditions. Soil from Sodosol sites which received less fertiliser P addition had the lowest orthophosphate concentration with only 57.6%. In contrast, relatively high proportions of organic P were found in soil samples from unfertilised Sodosol sites. On average, soil from Sodosol sites contained 37.5% organic P (combined monoester P and diester P), while those from Dermosol and Ferrosol sites contained 31.7% and 25.8%, respectively. Of these, the highest monoester phosphate proportions of 44.6% (site M3) and 46.4% (site M4) were found in Sodosol sites with no recent P inputs, but the highest proportion of diester phosphate (5.7%) was found in an unclassified grey sandy loam Dermosol. The higher organic P concentrations in soil from Sodosol sites may be associated with more regular moisture input from both rainfall and boarder-check (flood) irrigation. The highest level of pyrophosphate (8.5%) was also found in a grey/yellow Sodosol. Overall, the results indicate that P speciation in the Australian soils is strongly influenced by soil type, fertiliser P application rate and timing, and moisture variations. Full article
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