bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection and localization of impulsive sound events for environmental noise assessment
Authors: Wessels Peter W. , Sande Jeroen v. , Van der Eerden Frits
Published: June 2017

At military training areas events are created that can be heard kilometers away. The noise levels are subject to variation, mostly due to changes in meteorological conditions. The variation of these events is of importance for environmental noise assessment. Results are presented on the design of a system that automatically detects and localizes these events. It is based on a coarse grid of measurement units that detect relevant acoustic events within the training area. The locations of the events are obtained with a time difference of arrival method and detections from multiple measurement units, including dynamic corrections for meteorological effects. The performance of the system is evaluated with a large set of augmented audio files for different ranges. This set is based on a collection of source measurements of several heavy weapon types. A model that includes the attenuation due to ground and the meteorology is used to extrapolate the audio to more distant locations. The audio is also mixed with relevant background noise for a broad range of wind speeds. With the obtained detection and localization information it is possible to estimate the source levels of events and to extrapolate the measured sound levels to other locations of interest.
The relative importance of static versus spectral change acoustic features for automatic speaker identification
Authors: Zahorian Stephen , Guzewich Peter , Chen Xiao , Sadeghian Roozbeh , Zhang Hao
Published: June 2017

For at least two decades, the primary acoustic features used for both automatic speech recognition (ASR) and automatic speaker identification (SID) have been Mel frequency cepstral coefficients (MFCCs) and their first and second order difference terms, referred to as Delta and double Delta terms. The MFCC’s capture static spectral information, whereas the Delta terms capture spectral change information. In this experimental paper, we first reformulate the MFCC’s and Delta terms, as discrete cosine transform coefficients (DCTCs), which take the place of the MFCC’s, and discrete cosine series coefficients (DCSCs), which take the place of the Delta terms. Low dimensionality DCSC spaces (spectral change) result in very poor speaker discriminability, as compared to discriminability based on DCTCs. However, reasonably accurate automatic speaker identification can be achieved in a high dimensionality DCSC space. Combining DCTC terms and DCSC terms results in only modest improvements in identification accuracy over what can be achieved with DCTC terms alone. We conclude, for the purposes of automatic speaker identification, static spectral information is far more informative than spectral change information. The results of this study, plus results in the literature, support the hypothesis that a similar conclusion could be reached for human ability to recognize speakers.
Variations in impact sound level as a function of tapping machine position
Authors: LoVerde John , Dong David W.
Published: June 2017

Impact insulation class testing per ASTM E 492 requires measurement of the sound field at exactly four tapping machine positions. Previous research by the authors [J. Acoust. Soc. Am. 121, 3113 (2007), J. Acoust. Soc. Am. 122, 2955 (2007)] indicated that for field tests, the variation between tapping machine positions was small. To our knowledge, a systematic investigation has not been performed for tapping machine positions in the laboratory, and some recent results indicate that the variation may be larger than expected. Large variation in sound level may be inherent to the method, or may point to problems in construction or installation of flooring materials. The variations with tapping machine position are analyzed for a set of laboratory tests, and the previous field test studies are updated with additional data. The authors investigate possible changes to the standards to mandate a maximum allowable variation between tapping machine positions, and to require additional positions as necessary.
Update on sound quality assessment with TWO!EARS
Authors: Raake Alexander , Skowronek Janto , Wierstorf Hagen , Hold Christoph
Published: June 2017

The paper summarizes the different test and modeling campaigns carried out in the EC-funded FET-Open project TWO!EARS (www.twoears.eu) for sound quality and Quality of Experience (QoE) evaluation of spatial audio reproduction technology like stereophony or Wave-field Synthesis (WFS). This work represents one of the two proof-of-concept application domains of the interactive listening model developed in TWO!EARS. One stream of our sound-quality-related work focused on listening tests and model development for the individual sound quality features localization and coloration. After briefly reviewing the modeling approaches for these individual features presented in more depth elsewhere, the paper presents data and modeling considerations for a set of pairwise preference listening tests, following a dedicated audio mixing and reproduction paradigm. For subsequent model development, the results are analyzed in different ways, for example in terms of the pairwise preference data directly, using the Bradley-Terry-Luce model and using multidimensional analysis techniques. Based on these analyses, different modeling approaches based on the TWO!EARS framework are presented. To conclude, considerations are provided on how multimodal interaction can affect preference selections, based on an additional test on the selection of the “sweet spot” in a spatial audio listening context.
Implications of covert articulatory variation for several phonetic variables in Raleigh, North Carolina English
Authors: Mielke Jeff , Smith Bridget , Fox Michael J.
Published: June 2017

We examine several phonological variables in a spontaneous speech corpus and a lab-collected acoustic/articulatory dataset, in order to pursue the hypothesis that covert inter-speaker differences in speech production are instrumental to solving the actuation problem in language change. We examine two known cases of covert articulatory variation and their impact on a range of low-level and high-level sound patterns active in Raleigh, NC. The covert articulatory variables are /ɹ/ tongue shape and /l/ posterior constriction location. The overt variables are the retraction of /s/ and /z/ and the affrication of /t/ and /d/ in various contexts near /ɹ/ (within words and across word boundaries), flapping and deletion of /ɹ/ after /θ/, intrusive [ɫ] next to /θ/ and nasals, and the quality of vowels before and after /l/. We also examine affrication of /t/ and /d/ before /w/. The spontaneous speech comes from 132 hour-long interviews from the Raleigh Corpus (Dodsworth and Kohn 2012), and the lab speech is a set of 29 wordlist recordings exhibiting the overt variables under investigation. We report the observed relationships between the production of the covert and overt variables in the lab speech, and relate this to the distribution of variants in spontaneous speech.
Combating impulsive noise for multicarrier underwater acoustic communications
Authors: Liu Zhiqiang
Published: June 2017

This paper presents a novel multicarrier communication scheme that is specially designed for underwater acoustic channels with dominant impulsive noise. A novel multicarrier signaling structure is introduced at the transmitter. Thanks to the signaling structure, the received signal is shown satisfying some special properties even after various channel distortions. By exploiting these properties, we propose two receiver processing algorithms, one for signaling parameter estimation and the other for symbol recovery. The two algorithms take fully into account the presence of strong impulsive noise, and both are shown capable of offering inherent robustness against it. The proposed design is first evaluated via extensive simulations and then tested in a recent sea-going experiment. Both simulated and experimental results validate the proposed design and confirm its merits. [This work was supported by US Office of Naval Research.]
Nuance is dead (or What You Will)
Authors: Pfeiffer Scott D.
Published: June 2017

Live performance is about connection. Traditional amplification at its least effective introduces microphones and loudspeakers in between the artist with a message and the audience intending to show appreciation for the effort. The authenticity of performance in the right setting where the mircophones and loudspeakers are unnecessary can be deeply moving, and provides for an unambiguous exchange between performer and audience when the quality of the environment for the purpose is up to the challenge. The “Unplugged” movement in popular music of the early 90s attempted to bridge this gap, though clearly none of the acts was truly “Unplugged.” For all of acoustic design history, architectural or electronic technology to enhance the natural acoustic connection between performer and audience. Thanks to the efforts, we can replicate aspects of natural acoustics of a human scale—and the connection created by the shared environment—to make an under-performing acoustic environment better, a great acoustic environment more flexible, or simply create an interior acoustic where none exists. Applications and limitations of the available technologies for fictionalizing acoustic traits are explored to help recognize when the technology, architectural or electronic, becomes a distraction from the purpose.
Perceptually motivated sound field synthesis for music presentation
Authors: Ziemer Tim
Published: June 2017

The conceptualization and implementation of a psychoacoustic sound field synthesis system for music is presented. Critical bands, the precedence effect, and integration times of the auditory system as well as the radiation characteristics of musical instruments are implemented in the signal processing. Interaural coherence, masking and auditory scene analysis principles are considered as well. The sound field synthesis system creates a natural, spatial sound impression and precise source localization for listeners in extended listening area, even with a low number of loudspeakers. Simulations and a listening test provide a proof of concept. The method is particularly robust for signals with impulsive attacks and quasi-stationary phases as in the case of many instrumental sounds. It is compatible with many loudspeaker setups, such as 5.1, ambisonics systems and loudspeaker arrays for wave front synthesis. The psychoacoustic sound field synthesis approach is an alternative to physically centered wave field synthesis concepts and conventional stereophonic sound and can benefit from both paradigms. Additional psychoacoustic quantities that have the potential to be implemented in the presented and other audio systems are discussed.
A “composite” stepped plate for use in highly directional parametric array loudspeakers
Authors: Hwang Yonghwan , Kim Chayeong , Moon Wonkyu
Published: June 2017

It has been shown that stepped plate radiators with appropriately designed steps can be used in highly directional parametric array (PA) loudspeakers [Hwang and Moon, 170th Meeting of the Acoustical Society of America, 138(3), 1801(2015)]. To improve the performance of the PA loudspeaker, a relatively thin plate with steps needs to be adopted for its higher power efficiency. However, the natural frequencies of the plate and the corresponding mode shapes depend on the mass of the steps. Hence, it can be difficult to design a stepped plate suitable for use in PA loudspeakers. In this paper, we propose a novel plate design, with steps composed of a stiff, lightweight, polymer material. The steps were fabricated with a thickness of 2.3 mm from a polymer material with an elastic modulus of 1 GPa, a Poisson ratio of 0.23, and a mass density of 540 kg/m3 on the plate with a thickness of 1 mm. Experiments and simulations were carried out to determine the acoustic characteristics of our fabricated “composite” stepped plate. [Work supported by NRF 2016R1E1A2A02945515).]
Benchmark cases for urban sound propagation
Authors: Trikootam Sai Charan , Hornikx Maarten , Fernandes Gerson C. , van Hooff Twan , Blocken Bert , Van Renterghem Timothy
Published: June 2017

Urban sound propagation is influenced by multiple reflections on horizontal and vertical surfaces, either specular or diffusive in nature, diffraction around edges and meteorology, causing refraction and scattering of sound waves. This paper initiates multiple benchmark cases for urban sound propagation, with the purpose of comparing the suitability of computational methodologies. The benchmark cases are two-dimensional cross-sections of typical urban geometries, involving all of the effects mentioned above. The sound source is either geometrically screened or is in the line of sight from the receiver's position. When meteorological conditions are included, results obtained from computational fluid dynamics simulations are used. All details of the benchmark cases are concisely described, and results from two numerical methods for outdoor sound propagation are included. Both methods solve the linearized Euler equations (LEE). The first method is the Fourier pseudospectral time-domain method (Fourier-PSTD) implemented in the open source software openPSTD v2.0. The second method is the finite difference time domain method FDTD. A detailed comparison of the results obtained from the two methods is presented.
Fast iterative solution of acoustic multiple scattering problems
Authors: Amirkulova Feruza
Published: June 2017

Multiple scattering (MS) of waves by a system of scatterers is of great theoretical and practical importance. It is required in a wide variety of physical contexts such as the implementation of “invisibility” cloaks, the effective parameter characterization, etc. An iteratively computable Neumann series (NS) expansion technique is employed to expedite the MS solution. The method works if the spectral radius of the interaction matrix is less than one. The spectral properties of this matrix are investigated for different configurations of cylinders; the validity of solution is shown by modifying the number of scatterers M and their separation distance, d. The iterative solution works well for two rigid cylinders at any considered values of frequency,ω and d. The results show that the iterative algorithm is fast. The convergence rate analysis shows that the effectiveness of technique depends on the M, ω and d. Shrinking d, and rising M and ω weaken the convergence. We improve the algorithm by accelerating the overall convergence characteristics of NS. We use matrix manipulation and renormalization techniques provided for MS of fast atomic nuclei to improve NS convergence, and employ Padé approximants to expand the validity range of NS solutions. The iterative approach can be extended for a band of frequencies, and applied for multi-frequency wave propagation problems.
Ground Reaction Forces During Sprinting in Unilateral Transfemoral Amputees
Authors: Makimoto Atsushi , Sano Yoko , Hashizume Satoru , Murai Akihiko , Kobayashi Yoshiyuki , Takemura Hiroshi , Hobara Hiroaki
Published: June 2017

Understanding the characteristics of ground reaction forces (GRFs) on both limbs during sprinting in unilateral amputees wearing running-specific prostheses would provide important information that could be utilized in the evaluation of athletic performance and development of training methods in this population. The purpose of this study was to compare GRFs between intact and prosthetic limbs during sprinting in unilateral transfemoral amputees wearing running-specific prostheses. Nine sprinters with unilateral transfemoral amputation wearing the same type of prosthesis performed maximal sprinting on a 40-m runway. GRFs were recorded from 7 force plates placed in the center of the runway. Peak forces and impulses of the GRFs in each direction were compared between limbs. Peak forces in vertical, braking, propulsive, and medial directions were significantly greater in intact limbs than those in prosthetic limbs, whereas there were no significant differences in peak lateral force between limbs. Further, significantly less braking impulses were observed in prosthetic limbs than in intact limbs; however, the other measured impulses were not different between limbs. Therefore, the results of the present study suggest that limb-specific rehabilitation and training strategies should be developed for transfemoral amputees wearing running-specific prostheses.
Effects of Hip Strengthening on Neuromuscular Control, Hip Strength, and Self-Reported Functional Deficits in Individuals With Chronic Ankle Instability
Authors: Smith Brent I. , Curtis Denice , Docherty Carrie L.
Published: June 2017

Context: Deficits in ankle and hip strength and lower-extremity postural control are associated with chronic ankle instability (CAI). Following strength training, muscle groups demonstrate increased strength. This change is partially credited to improved neuromuscular control, and many studies have investigated ankle protocols for subjects with CAI. The effects of isolating hip musculature in strength training protocols in this population are not well understood. Objective: To examine the effects of hip strengthening on clinical and self-reported outcomes in patients with CAI. Design: Prospective randomized controlled clinical trial. Setting: Athletic training facility. Participants: Twenty-six participants with CAI (12 males and 14 females; age = 20.9 [1.5] y, height = 170.0 [12.7] cm, and mass = 77.5 [17.5] kg) were randomly assigned to training or control groups. Intervention: Participants completed either 4 weeks of supervised hip strengthening (resistance bands 3 times a week) or no intervention. Main Outcome Measures: Participants were assessed on 4 clinical measures (Star Excursion Balance Test in the anterior, posteromedial, and posterolateral directions; Balance Error Scoring System; hip external rotation strength; and hip abduction strength) and a patient-reported measure (the Foot and Ankle Ability Measure activities of daily living and sports subscales) before and after the 4-week training period. Results: The training group displayed significantly improved posttest measures compared with the control group for hip abduction strength (training: 446.3 [77.4] N, control: 314.7 [49.6] N, P < .01); hip external rotation strength (training: 222.1 [48.7] N, control: 169.4 [34.6] N, P < .01); Star Excursion Balance Test reach in the anterior (training: 93.1% [7.4%], control: 90.2% [7.9%], P < .01), posteromedial (training: 96.3% [8.9%], control: 88.0% [8.8%], P < .01), and posterolateral (training: 95.4% [11.1%], control: 86.6% [9.6%], P < .01) directions; Balance Error Scoring System total errors (training: 9.9 [6.3] errors, control: 21.2 [6.3] errors, P < .01); and the Foot and Ankle Ability Measure-sports score (training: 88.0 [12.6], control: 84.8 [10.9], P < .01). Conclusion: Improved clinical and patient-reported outcomes in the training group suggest hip strengthening is beneficial in the management and prevention of recurrent symptoms associated with CAI.
Sensorimotor Control of the Shoulder in Professional Volleyball Players With Isolated Infraspinatus Muscle Atrophy
Authors: Contemori Samuele , Biscarini Andrea , Botti Fabio M. , Busti Daniele , Panichi Roberto , Pettorossi Vito E.
Published: June 2017

Context: Isolated infraspinatus muscle atrophy (IIMA) affects only the hitting shoulder of overhead-activity athletes and is caused by suprascapular nerve neuropathy. No study has assessed the static and dynamic stability of the shoulder in overhead professional athletes with IIMA to reveal possible shoulder sensorimotor alterations. Objective: To assess the shoulder static stability, dynamic stability, and strength in professional volleyball players with IIMA and in healthy control players. Design: Cross-sectional study. Setting: Research lab. Patients or Other Participants: A total of 24 male professional volleyball players (12 players with diagnosed IIMA and 12 healthy players) recruited from local volleyball teams. Intervention(s): Static stability was evaluated with 2 independent force platforms, and dynamic stability was assessed with the “Upper Quarter Y Balance Test.” Main Outcome Measure(s): The static stability assessment was conducted in different support (single hand and both hands) and vision (open and closed eyes) conditions. Data from each test were analyzed with analysis of variance and paired t-test models to highlight statistical differences within and between groups. Results: In addition to reduced abduction and external rotation strength, athletes with IIMA consistently demonstrated significant less static (P < .001) and dynamic stability (P < .001), compared with the contralateral shoulder and with healthy athletes. Closed eyes condition significantly enhanced the static stability deficit of the shoulder with IIMA (P = .04 and P = .03 for both hand and single hand support, respectively) but had no effect on healthy contralateral and healthy players’ shoulders. Conclusions: This study highlights an impairment of the sensorimotor control system of the shoulder with IIMA, which likely results from both proprioceptive and strength deficits. This condition could yield subtle alteration in the functional use of the shoulder and predispose it to acute or overuse injuries. The results of this study may help athletic trainers and physical/physiotherapists to prevent shoulder injuries and create to specific proprioceptive and neuromuscular training programs.
The Validity and Reliability of Knee Proprioception Measurement Performed With Inclinometer in Different Positions
Authors: Suner-Keklik Sinem , Cobanoglu-Seven Gamze , Kafa Nihan , Ugurlu Mustafa , Guzel Nevin Atalay
Published: June 2017

Context: Proprioception is the basic element of the spontaneous control of movement, balance and joint stability. Therefore, it is necessary for the execution of walking and daily and sport activities. Loss of proprioception of the knee, which may cause a new injury, is important to evaluate the position sense of the joint during the rehabilitation period. However, the evaluation methods that are used are very expensive, complicated and nonportable, or the measuring method is difficult to implement. Objective: We demonstrated the validity and reliability of knee proprioception measurements performed in the open kinetic chain position and closed kinetic chain position with a dual inclinometer. Design: We assessed the validity and intratester reliability of a digital inclinometer for measuring the knee joint position sense in different positions. Setting: Clinical laboratory. Participants: We enrolled 22 participants (age = 21.8 ± 0.95 y, height = 172 ± 9.1 cm, weight = 64.9 ± 14 kg) into the study. Intervention: The same investigator used an inclinometer to take knee proprioception measurements in open and closed kinetic chain positions. Main Outcome Measures: The relative angular error was calculated by taking the arithmetic average of the difference between the target angle and reproduced angle and was the main outcome measure. Results: We found that the dynamometer-inclinometer had a moderate ICC value (ICC = 0.594, SEM = 1.60, P = .005), whereas inclinometer t1 vs inclinometer t2 (ICC = 0.778, SEM = 0.62, P < 0.001) and closed kinetic chain position t1 and closed kinetic chain position t2 (ICC = 0.888, SEM = 0.63, P < 0.001) had high ICC values. Conclusion: Knee proprioception measurements performed with a dual inclinometer were reliable in the closed kinetic chain position in healthy, sedentary individuals and were valid and reliable in the open kinetic chain position.
Stroboscopic Vision to Induce Sensory Reweighting During Postural Control
Authors: Kim Kyung-Min , Kim Joo-Sung , Grooms Dustin R.
Published: June 2017

Context: Patients with somatosensory deficits have been found to rely more on visual feedback for postural control. However, current balance tests may be limited in identifying increased visual dependence (sensory reweighting to the visual system), as options are typically limited to eyes open or closed conditions with no progressions between. Objective: To assess the capability of stroboscopic glasses to induce sensory reweighting of visual input during single-leg balance. Design:Descriptive Setting: Laboratory Participants: 18 healthy subjects without vision or balance disorders or lower extremity injury history (9 females; age = 22.1 ± 2.1 y; height = 169.8 ± 8.5 cm; mass = 66.5 ± 10.6 kg) participated. Interventions: Subjects performed 3 trials of unipedal stance for 10 s with eyes open (EO) and closed (EC), and with stroboscopic vision (SV) that was completed with specialized eyewear that intermittently cycled between opaque and transparent for 100 ms at a time. Balance tasks were performed on firm and foam surfaces, with the order randomized. Main Outcome Measures: Ten center-of-pressure parameters were computed. Results: Separate ANOVAs with repeated measures found significant differences between the 3 visual conditions on both firm (P-values =< .001) and foam (P-values =< .001 to .005) surfaces for all measures. For trials on firm surface, almost all measures showed that balance with SV was significantly impaired relative to EO, but less impaired than EC. On the foam surface, almost all postural stability measures demonstrated significant impairments with SV compared with EO, but the impairment with SV was similar to EC. Conclusions:SV impairment of single-leg balance was large on the firm surface, but not to the same degree as EC. However, the foam surface disruption to somatosensory processing and sensory reweighting to vision lead to greater disruptive effects of SV to the same level as EC. This indicates that when the somatosensory system is perturbed even a moderate decrease in visual feedback (SV) may induce an EC level impairment to postural control during single-leg stance.
Acute Compensatory Responses to Interrupting Prolonged Sitting With Intermittent Activity in Preadolescent Children
Authors: O’Sullivan Molly P. , Nagy Matthew R. , Block Shannon S. , Tooley Trevor R. , Robinson Leah E. , Colabianchi Natalie , Hasson Rebecca E.
Published: June 2017

Purpose: The purpose of this study was to compare the effects of intermittent activity performed at varying intensities and of prolonged sitting on physical activity compensation. Methods: A total of 33 children (14 boys and 19 girls; age 7–11 y; 24% overweight/obese; 61% nonwhite) completed 4 experimental conditions in random order: 8 hours of sitting interrupted with 20 two-minute low-, moderate-, or high-intensity activity breaks or 20 two-minute sedentary computer game breaks. Physical activity energy expenditure (PAEE) was assessed via accelerometry to establish baseline PAEE and throughout each condition day (8-h in-lab PAEE, out-of-lab PAEE, and 3-d postcondition). Results: Compared with baseline PAEE, total daily PAEE was significantly higher during the high-intensity condition day (153 ± 43 kcal, P = .03), unchanged during the low-intensity (−40 ± 23 kcal, P > .05) and moderate-intensity condition days (−11 ± 18 kcal, P > .05), and decreased in response to prolonged sitting (−79 ± 22 kcal, P = .03). There were no significant differences in PAEE 3-day postcondition across conditions (P > .05). Conclusion: Despite the varying levels of PAEE accumulated during the 8-hour laboratory conditions, out-of-lab PAEE during each condition day and 3-day postcondition did not change from the baseline. These findings provide preliminary evidence that spontaneous physical activity in children does not change in response to intermittent activity or prolonged sitting.
Effects of macro- and micronutrients on exercise-induced hepcidin response in highly trained endurance athletes
Authors: Dahlquist Dylan T. , Stellingwerff Trent , Dieter Brad P. , McKenzie Donald C. , Koehle Michael S.
Published: June 2017

Iron deficiency has ergolytic effects on athletic performance. Exercise-induced inflammation impedes iron absorption in the digestive tract by upregulating the expression of the iron regulatory protein, hepcidin. Limited research indicates the potential of specific macro- and micronutrients on blunting exercise-induced hepcidin. Therefore, we investigated the effects of postexercise supplementation with protein and carbohydrate (CHO) and vitamins D3 and K2 on the postexercise hepcidin response. Ten highly trained male cyclists (age: 26.9 ± 6.4 years; maximal oxygen uptake: 67.4 ± 4.4 mL·kg–1·min–1 completed 4 cycling sessions in a randomized, placebo-controlled, single-blinded, triple-crossover study. Experimental days consisted of an 8-min warm-up at 50% power output at maximal oxygen uptake, followed by 8 × 3-min intervals at 85% power output at maximal oxygen uptake with 1.5 min at 60% power output at maximal oxygen uptake between each interval. Blood samples were collected pre- and postexercise, and at 3 h postexercise. Three different drinks consisting of CHO (75 g) and protein (25 g) with (VPRO) or without (PRO) vitamins D3 (5000 IU) and K2 (1000 μg), or a zero-calorie control drink (PLA) were consumed immediately after the postexercise blood sample. Results showed that the postexercise drinks had no significant (p ≥ 0.05) effect on any biomarker measured. There was a significant (p < 0.05) increase in hepcidin and interleukin-6 following intense cycling intervals in the participants. Hepcidin increased significantly (p < 0.05) from baseline (nmol·L–1: 9.94 ± 8.93, 14.18 ± 14.90, 10.44 ± 14.62) to 3 h postexercise (nmol·L–1: 22.27 ± 13.41, 25.44 ± 11.91, 22.57 ± 15.57) in VPRO, PRO, and PLA, respectively. Contrary to our hypothesis, the drink compositions used did not blunt the postexercise hepcidin response in highly trained athletes.
Influence of electro-osmosis activation time on vacuum electro-osmosis consolidation of a dredged slurry
Authors: Wang Jun , Fu Hongtao , Liu Feiyu , Cai Yuanqiang , Zhou Jie
Published: June 2017

Combining vacuum preloading with electro-osmosis of a dredged slurry is a significantly effective technology for ground improvement. Despite extensive research, the mechanism of vacuum preloading combined with electro-osmosis is still not properly understood, especially regarding the optimum electro-osmosis activation time. In this study, laboratory tests were performed to confirm the influence of electro-osmosis activation time on vacuum electro-osmosis consolidation of a dredged slurry. A total voltage of 12 V was used in five tests with different electro-osmosis activation times. During the combined process of vacuum preloading and electro-osmosis, the vacuum pressure, electric current, and volume of extracted water were monitored. The water content and shear strength were measured after the tests. The results indicated that electro-osmosis was activated when the degree of consolidation for the soil reached 60%. Thus, this approach can significantly promote the effectiveness of soil consolidation. The shear strength distribution along the depth was much more uniform in all tests with electro-osmosis. The shear strength decreased linearly with increasing distance from the anode rows, but sharp increases occurred near the cathode row (or prefabricated vertical drains).
Interval Estimation of Relative Values in Residue Number System
Authors: Isupov Konstantin , Knyazkov Vladimir
Published: June 2017

Residue number system (RNS), due to its carry-free nature, is popular in many applications of high-speed computer arithmetic, especially in digital signal processing and cryptography. However, the main limiting factor of RNS is a high complexity of such operations as magnitude comparison, sign determination and overflow detection. These operations have, for many years, been a major obstacle to more widespread use of parallel residue arithmetic. This paper presents a new efficient method to perform these operations, which is based on computation and analysis of the interval estimation for the relative value of an RNS number. The estimation, which is called the interval floating-point characteristic (IFC), is represented by two directed rounded bounds that are fixed-precision numbers. Generally, the time complexities of serial and parallel computations of IFC are linear and logarithmic functions of the size of the moduli set, respectively. The new method requires only small-integer and fixed-precision floating-point operations and focuses on arbitrary moduli sets with large dynamic ranges ([Formula: see text]). Experiments indicate that the performance of the proposed method is significantly higher than that of methods based on Mixed-Radix Conversion.
INVESTIGATING THE IMPLEMENTATION OF ZnO NANOPARTICLES AS A TUNABLE UV DETECTOR FOR DIFFERENT SKIN TYPES
Authors: MOSAYEBI PEGAH , DORRANIAN DAVOUD , BEHZAD KASRA
Published: June 2017

A facile chemical reduction method was used to synthesize ZnO nanoparticles (NPs) in ethylene glycol solvent at two different calcination temperatures. As a result of variation in the calcination temperature, ZnO NPs with two different sizes were achieved. The NPs were investigated for their structural and optical characteristics using X-ray diffraction and ultraviolet (UV)–Vis spectroscopy. The synthesized ZnO NPs exhibited a hexagonal structure with sizes of 46 and 65[Formula: see text]nm. The synthesized NPs were then used to investigate dye photocatalytic behavior of products as a tunable UV detector for different skin types. The dye degradation and decolorization of methylene blue in the presence of ZnO NP, following UV radiation as a function of time, were studied at different pH levels. The optical absorption spectra were then taken every 15[Formula: see text]min for all samples. The UV–Vis spectroscopy spectra revealed that optical absorption of solution was decreased upon UV exposure as a function of time. Photocatalytic reaction indicated that the dye degradation and decolorization rate were accelerated with the increase of pH level. Therefore, a tunable UV detector for different skin types could be engineered by varying the pH level of solution to avoid human skin burning.
Contextuality with a small number of observables
Authors: Holweck Frédéric , Saniga Metod
Published: June 2017

We investigate small geometric configurations that furnish observable-based proofs of the Kochen–Specker theorem. Assuming that each context consists of the same number of observables and each observable is shared by two contexts, it is proved that the most economical proofs are the famous Mermin–Peres square and the Mermin pentagram featuring, respectively, 9 and 10 observables, there being no proofs using less than 9 observables. We also propose a new proof with 14 observables forming a “magic” heptagram. On the other hand, some other prominent small-size finite geometries, like the Pasch configuration and the prism, are shown not to be contextual.
HOW DO FIRMS OPEN UP THE FRONT-END OF SERVICE INNOVATION? A CASE STUDY OF IT-BASED SERVICE FIRMS IN THAILAND
Authors: THANASOPON BUNDIT , PAPADOPOULOS THANOS , VIDGEN RICHARD
Published: June 2017

This paper focusses on the openness in the front-end phase of service innovation and its impact on innovation success. The early stages of innovation are fuzzy and unstructured, thus often being called “fuzzy front-end” (FFE) by scholars. The FFE begins when an opportunity is considered worthy of further ideation, exploration, and assessment and ends when a firm decides to invest in — or terminate — an idea. Although openness has been identified as pivotal to innovation performance, little effort has been put into exploring its role in the early phase of innovation. By drawing on the data of a multiple case study in Thai online service firms, we are able to identify four key dimensions of FFE openness competence: prior related knowledge, top management support, the presence of workable prototype, and slack resource. Furthermore, we found three openness activities that often take place in the FFE phase of successful online service innovation, i.e., external search, inter-firm partnerships and customer experimentation. From a managerial perspective, our study provides useful insights to innovation managers aiming at enhancing front-end performance through openness.
ORGANISATIONAL FACTORS, ANTICIPATED RENTS AND COMMERCIALISATION IN SMEs
Authors: DO HANG , MAZZAROL TIM , SOUTAR GEOFFREY N. , VOLERY THIERRY , REBOUD SOPHIE
Published: June 2017

The study investigates the relationship between organisational factors and the anticipated returns to the commercialisation of an innovation within small to medium enterprises (SMEs). Using a large multi-country sample, the analysis involved a structural equation model of seven organisational factors associated with the management of innovation, and their relationship with the anticipated volume of sales, profitability and lifecycle of the innovation. Significant relationships were found between the possession of an innovation strategy and formal commercialisation management, and optimism over sales volumes and lifecycle. The study provides new insights into the resource-based view and theory of entrepreneurial rents, strengthening SME owner-managers’ assessment on future investments in innovation and how to utilise their best capabilities. Policy makers also gain more insights into the commercialisation process within SMEs to foster the innovation orientation in both high and low tech sectors.
Design of an Optimal Preview Controller for a Class of Linear Discrete‐Time Descriptor Systems
Authors: Liao Fucheng , Xue Zhihua , Wu Jiang
Published: June 2017

The preview control problem of a class of linear discrete‐time descriptor systems is studied. Firstly, the descriptor system is decomposed into a normal system and an algebraic equation by the method of the constrained equivalent transformation. Secondly, by applying the first‐order forward difference operator to the state equation, combined with the error equation, the error system is obtained. The tracking problem is transformed into the optimal preview control problem of the error system. Finally, the optimal controller of the error system is obtained by using the related results and the optimal preview controller of the original system is gained. In this paper, we propose a numerical simulation method for descriptor systems. The method does not depend on the restricted equivalent transformation.
Forest Evapotranspiration and Energy Flux Partitioning Based on Eddy Covariance Methods in an Arid Desert Region of Northwest China
Authors: Ma Xiaohong , Feng Qi , Su Yonghong , Yu Tengfei , Jin Hua
Published: June 2017

In this study, the characteristics of energy flux partitioning and evapotranspiration of P. euphratica forests were examined in the extreme arid region of Northwest China. Energy balance closure of the ecosystem was approximately 72% (H + LE = 0.72 ∗ (Rn-G)+7.72, r2=0.79, n=12095), where Rn is the net radiation, G is the soil heat flux, H is the sensible heat flux, and LE is the latent heat flux. LE was the main term of energy consumption at annual time scale because of higher value in the growing season. The ratios of the latent (LE) and sensible (H) heat fluxes to net radiation were 0.47 and 0.28 throughout the year, respectively. Moreover, the yearly evapotranspiration of P. euphratica forests was 744 mm year−1. And the mean daily ET was 5.09 mm·d−1 in the vibrant growing season. In particular, a small spike in the actual evapotranspiration distribution occurred during the soil ablation period due to the higher temperature and sufficient soil moisture associated with soil thawing. This period is accompanied by a series of physical processes, such as moisture transfer and heat exchange.
Experimental Study on the Mechanical Properties of Porcine Cartilage with Microdefect under Rolling Load
Authors: Men Yu-tao , Li Xiao-ming , Chen Ling , Fu Hu
Published: June 2017

Objectives. To investigate the mechanical responses of microdefect articular cartilage under rolling load and find out the failure rule. Methods. Rolling load was applied to the porcine articular cartilage samples with rectangular notches of different depths. The displacement and strain near the notches were obtained by the noncontact digital image correlation technique. Results. The strain value and peak frequency around the notch increased; the maximum equivalent strain value could be observed at both bottom corners of the notch; the equivalent strain value first increased and then decreased at the points in the superficial and middle layers with the increase of rolling velocity; the points in the deep layer were less affected by rolling velocity; the equivalent strain value of the points in the superficial layer declined after rising with the increase of defect depth, while a decreased trend could be found for the points in the middle and deep layers. Conclusions. The shear strain, which rose with the increase in defect depth, was the main factor in cartilage destruction. The cartilage tended to be destructed firstly at the bottom corner of the defect. Rolling velocity showed significant effects on superficial and middle layers. Cartilage had the ability to resist destruction.
Convergent Properties of Riccati Equation with Application to Stability Analysis of State Estimation
Authors: Cai X. , Ding Y. S. , Li S. Y.
Published: June 2017

Since the recursive nature of Kalman filtering always results in a growing size of the optimization problem, state estimation is usually realized by use of finite‐memory, receding horizon, sliding window, or “frozen” techniques, which causes difficulties on stability analysis. This paper proposes a novel method on selection of an initial covariance matrix and a horizon for the Kalman filter to make sure that a sequence of the closed‐loop Kalman filters are stable as time‐invariant filters at subsequent time instant. Convergent properties of Riccati Difference Equation (RDE) are first exploited. Based on these properties, sufficient conditions for stability of a sequence of Kalman filters are obtained. Compared with the existent literature, the convergent properties and the stability conditions are less conservative since they provide analytic results and are applicable to more common cases where the RDEs are not monotonic.
Optimal and Nonlinear Dynamic Countermeasure under a Node-Level Model with Nonlinear Infection Rate
Authors: Zhang Xulong , Gan Chenquan
Published: June 2017

This paper mainly addresses the issue of how to effectively inhibit viral spread by means of dynamic countermeasure. To this end, a controlled node-level model with nonlinear infection and countermeasure rates is established. On this basis, an optimal control problem capturing the dynamic countermeasure is proposed and analyzed. Specifically, the existence of an optimal dynamic countermeasure scheme and the corresponding optimality system are shown theoretically. Finally, some numerical examples are given to illustrate the main results, from which it is found that (1) the proposed optimal strategy can achieve a low level of infections at a low cost and (2) adjusting nonlinear infection and countermeasure rates and tradeoff factor can be conductive to the containment of virus propagation with less cost.
Purification and Characterization of an ATPase GsiA from Salmonella enterica
Authors: Wang Zhongshan , Zhang Meng , Shi Xiaodong , Xiang Quanju
Published: June 2017

The coding sequence of Salmonella enterica gsiA was cloned and expressed in E. coli. The protein was purified and ATPase activity was characterized by NADH oxidation method. GsiA exhibited optimum activity at 30°C and at pH 8 in Tris/HCl buffer. GsiA protein was stable at 20°C. 66% and 44% activity remained after incubation at 30°C and 40°C for 30 min. pH 7 and pH 9 incubation would obviously reduce the ATPase activity. In vivo functionality of gsiA was determined by constructing gene deletion strains. gsiA was shown to be essential for GSI mediated glutathione uptake and gsiA deletion could decrease the virulence of Salmonella enterica. Interactions of glutathione import proteins GsiA, GsiB, GsiC, and GsiD were investigated by using bacterial two-hybrid system. GsiA could interact with itself and inner membrane proteins GsiC and GsiD. This report provides the first description of gsiA functions in Salmonella enterica. The results could help elucidating the glutathione uptake mechanism and glutathione functions in bacteria.
Study on the Noise Reduction of Vehicle Exhaust NOX Spectra Based on Adaptive EEMD Algorithm
Authors: Zhang Kai , Zhang Yujun , You Kun , He Ying , Gao Qiankun , Liu Guohua , He Chungui , Lu Yibing , Fan Boqiang , Tang Qixing , Liu Wenqing
Published: June 2017

It becomes a key technology to measure the concentration of the vehicle exhaust components with the transmission spectra. But in the conventional methods for noise reduction and baseline correction, such as wavelet transform, derivative, interpolation, polynomial fitting, and so forth, the basic functions of these algorithms, the number of decomposition layers, and the way to reconstruct the signal have to be adjusted according to the characteristics of different components in the transmission spectra. The parameter settings of the algorithms above are not transcendental, so with them, it is difficult to achieve the best noise reduction effect for the vehicle exhaust spectra which are sharp and drastic in the waveform. In this paper, an adaptive ensemble empirical mode decomposition (EEMD) denoising model based on a special normalized index optimization is proposed and used in the spectral noise reduction of vehicle exhaust NOX. It is shown with the experimental results that the method can effectively improve the accuracy of the spectral noise reduction and simplify the denoising process and its operation difficulty.
Axially Symmetric Null Dust Space-Time, Naked Singularity, and Cosmic Time Machine
Authors: Ahmed Faizuddin
Published: June 2017

We present a gravitational collapse null dust solution of the Einstein field equations. The space-time is regular everywhere except on the symmetry axis where it possesses a naked curvature singularity and admits one parameter isometry group, a generator of axial symmetry along the cylinder which has closed orbits. The space-time admits closed timelike curves (CTCs) which develop at some particular moment in a causally well-behaved manner and may represent a Cosmic Time Machine. The radial geodesics near the singularity and the gravitational lensing (GL) will be discussed. The physical interpretation of this solution, based on the study of the equation of the geodesic deviation, will be presented. It was demonstrated that this solution depends on the local gravitational field consisting of two components with amplitudes Ψ2 and Ψ4.