Bandwidth Changes Research Articles

The relationship between vowel space area and intelligibility of speech in children with velopharyngeal insufficiency

Speech of individuals with velopharyngeal insufficiency is characterized by nasalized vowels. It is well known that velopharyngeal coupling significantly alters the acoustic spectrum of vowels. Aside from changes in formant amplitude and bandwidth, formant frequencies may be modified. Centralized F1 and lowered F2 due to effects of nasalization could change the dimensions of the quadrilateral space. Such variations might cause the vowel space area to be compressed which might contribute to speech unintelligibility. In pursuing research on speech intelligibility in cleft palate, this study was conducted to address the relation between speech intelligibility and spectral characteristics of American English vowels in nasal speech. The hypotheses is that narrower vowel space will result in higher degrees of unintelligibility. Ten children aged 4-12 years with different degrees of hypernasality repeated words with four corner vowels. F1 and F2 midpoint frequencies were measured, and vowel space areas were calculated using the formula for an irregular quadrilateral. In order to determine intelligibility, seventy naive listeners were asked to orthographically transcribe the sentences produced by the participants. Correlational analysis were used to determine the relationship between the vowel space and intelligibility deficits. Further results will be discussed in the meeting.

Reconfigurable thin film filter for compensating AOI deviation effects using LC coupled cavities

An efficient technique to enhance thin-film filters’ angular tolerance is described and numerically demonstrated. The spacer refractive index is controlled using a liquid crystal (LC) in the multi-cavity thin-film filter. The angle of incident (AOI) deviation causes significant degradation in the filter performance. To circumvent the influence of the AOI deviation, a correction effect is introduced through controlling the LC refractive index, while maintaining the normal incident performance of the filter. The proposed LC-based approach has proven effective in increasing the angular tolerance of the thin-film filter. Simulation results indicate an angle-insensitive performance under a 20o incident angle cone deviation. The results illustrate the effectiveness of this approach over the C-band, where the change in the center wavelength shift was reduced from 107.57 nm to 0.38 nm. Moreover, the change in the transmission filter bandwidth was reduced by 70%. The proposed compensation approach offers flexibility in the central wavelength and in the filter bandwidth estimated at the 0.5 dB, 3 dB, and 25 dB passband ranges.

Performance evaluation of Ce3+ doped flexible PVDF fibers for efficient optical pressure sensors

This work proposes a highly novel centrifugally spun lanthanide doped nonwoven fibrous mat as a non-contact optical pressure sensor with a wide linear dynamic range and good pressure sensitivity. The sensor properties are based on the spectral shift, broadening and intensity enhancement of Ce3+ ion in Ce doped PVDF fiber upto significantly high pressure. Two different systems: Ce(NO3)3·6H2O and (NH4)4Ce(SO4)4·2H2O doped PVDF flexible fibers (CeN-PF and CeS-PF) were produced using the Forcespinning® technique. Both CeN-PF and CeS-PF fibers displayed violet-blue emission under UV irradiation due to a 5d-4f transition of Ce3+ ions. Our emission results show that both CeN-PF and CeS-PF spectral characteristics are influenced by high pressures, inducing significant spectral ref shift in 5d-4f. The pressure-induced monotonous changes in bandwidth and emission intensity enhancement along with red shift suggesting the potential application of these fibers for pressure sensing applications. The CeN-PF fiber exhibits a high-pressure sensitivity (dλ/dP ≈ 0.28 nm/GPa) under a comprehensive linear dynamic range (0–64 GPa) with no pressure-induced luminescence quenching. The changes in CeS-PF is less pronounced with a lower pressure sensitivity of 0.10 nm/GPa compared to CeN-PF due to large crystal field splitting energy of nitrate ion compared to sulphate ion. This work presents a highly efficient, cost effective, scalable lanthanide doped flexible fibrous based system with negligible high pressure quenching and a wider linear dynamic range for optical pressure sensing applications.

PWRR Algorithm for Video Streaming Process Using Fog Computing

The most popular medium that being used by people on the internet nowadays is video streaming. Nevertheless, streaming a video consumes much of the internet traffics. The massive quantity of internet usage goes for video streaming that disburses nearly 70% of the internet. Some constraints of interactive media might be detached; such as augmented bandwidth usage and lateness. The need for real-time transmission of video streaming while live leads to employing of Fog computing technologies which is an intermediary layer between the cloud and end user. The latter technology has been introduced to alleviate those problems by providing high real-time response and computational resources near to the client at the network boundary. The present research paper proposes priority weighted round robin (PWRR) algorithm for streaming operations scheduling in the fog architecture. This will give preemptive for streaming live video request to be delivered in a very short response time and real-time communication. The results of experimenting the PWRR in the proposed architecture display a minimize latency and good quality of live video requests which has been achieved with bandwidth changes as well as meeting all other clients requests at the same time

FBG wavelength demodulation based on bandwidth of radio frequency signals

A FBG sensor real-time demodulation system based on radio frequency signals’ bandwidth monitoring is proposed. To the best of authors’ knowledge, this is the first FBG sensor demodulated by using radio frequency signals’ bandwidth. Beat frequency signals (BFS) are generated by multi-longitudinal mode laser in a laser cavity which is made of a sensing FBG, a static FBG and a piece of fiber. The sensing FBG’s center wavelength shift is in proportion to a bandwidth change of BFS. The demodulation system has a high sensitivity of 50.0 MHz/με. Measurement results demonstrated the system’s high accuracy, sensitivity and stability.

A bandwidth response humidity sensor with micro-nano fibre Bragg grating

Abstract A polyimide-coated fibre Bragg grating (FBG) relative humidity sensor with bandwidth response is proposed and demonstrated. A 12-μm-diameter micro-nano fibre is fabricated and the FBG was written by a 244-nm-UV laser, followed by the coating of polyimide on the FBG to form the sensor. The principle of the bandwidth response sensing based on the relationship between the humidity and the reflection spectra bandwidth is described. The sensor is examined under different relative humidity conditions. The results show that, with an increase in the relative humidity, the bandwidth changes at a rate of 0.00297 nm/%RH, and the linearity value is 99.3%. However, when the relative humidity is decrease, the linearity values are 97% and 98%, and the sensitivity values are 0.0035 nm/%RH and 0.0008 nm/%RH at ranges of 90–65 %RH and 65–30 %RH, respectively. In addition, the sensor has been tested the bandwidth change with temperature change under different humidity, the bandwidth-temperature sensitivity is about 0.35 pm/°C.

Modification of arms patch of double layer printed antenna for partial discharge detection

Partial discharge is a local electrification phenomenon that partially connects the insulation between the conductors and occurs either on the surface of the conductor or inside the conductor (void). PD generates several phenomena that accompany the occurrence of PD, such as impulse currents, hot light radiation, electromagnetic waves, mechanical waves, and chemical processes. This phenomenon is captured to know the existence of PD. One of the PD measurements uses the UHF method, i.e., by measuring the waves generated by the partial discharge. The antenna is one form of antenna developed from a square microstrip antenna with symmetrical T-shaped tethering. Antenna parameters can result in changes in return loss and VSWR measurements. The parameter change is done on three parameters, i.e. (A, B and G) showing the difference to the reference antenna. The experimental results show a change in antenna bandwidth.

Analysis of micro-structural damage evolution of concrete through coupled X-ray computed tomography and gray-level co-occurrence matrices method

Concrete CT test is an effective method used to analyze micro-structural damage evolution of concrete under loading condition. In the CT images of different stress states in the same section, gray value changes in the original number matrix of CT image are the key to investigate microscopic damage evolution of concrete. However, the slight changes in the gray value of CT images before peak stress cannot be intuitively observed with the naked eye. This study mainly aims to develop a coupled method based on statistical method and X-ray CT to extract indicators of such subtle changes. Different cross-sectional CT images of concrete at different stress stages were obtained by uniaxial static compression CT test. The theory of the grey level co-occurrence matrices (GLCM) was then adopted to analyze micro-damage evolution and crack properties. That is, the GLCM of the CT images were calculated, and four statistical features including contrast, energy, correlation, and homogeneity were extracted, which can be extended into quantitative analysis of micro-damage hidden in the CT images of concrete. Results exhibited that the damage growth area, concentrating between the 45th and 225th concrete cross-section, could be predicted by the distribution of four statistical features (i.e., contrast, energy, correlation and homogeneity) at the fourth scan, and it is consistent with the crack location in the fifth scan. The contrast, energy and homogeneity follow the Gaussian distribution under five scan stages, and the correlation follows the Laplace distribution. In addition, the changes of bandwidth in color heat map illustrating the GLCM before and after specimen failure show that the bandwidth is positively correlated with micro-structural damage of concrete specimen.

Scanning Spectrometer-on-a-Chip Using Thermo-Optical Spike-Filters or Vernier-Comb Filters

This theoretical modeling and simulation paper presents designs and projected performance of an on-chip scanning spectrometer using thermo-optical (TO) spike- or Vernier-comb filters operating around 3600 nm for the germanium-on-nitride technological platform. Raman spectra and absorption spectra are targeted. The spike filter consists of a thermo-optically tunable waveguide Bragg grating resonator (WBGR). The length of the WBGR is chosen to realize a Lorentzian resonant spectral profile with a bandwidth changing between 0.1 and 1 nm. The Vernier-comb filter is obtained using the cascade of two multi-Sagnac loop Mach–Zehnder interferometers, in which through the spectrum of the second MZI is shifted along the wavelength axis by means of a low-power TO heater stripe atop each loop-connector. The sagnac loop reflectors length is designed according to the wavelength-channel spacing requirements in order to induce the Type-1 Vernier effect. Time-scanned discrete sampling of the unknown input spectrum is obtained by driving the TO heater stripe with a periodic ramp current. We examined the device performance in terms of signal reconstruction in the mid-infrared region. The investigation demonstrated that high quality spectrum reconstruction is obtained for arbitrary input signals with an observation wavelength range from 23.4 to 77.4 nm. We also show that spectrum reconstruction of arbitrary signals is feasible in the germanium on nitride chips even in presence of additive noise.

Determination of optimal bandwidth in upscaling process of reservoir data using kernel function bandwidth

Upscaling based on the bandwidth of the kernel function is a flexible approach to upscale the data because the cells will be coarse-based on variability. The intensity of the coarsening of cells in this method can be controlled with bandwidth. In a smooth variability region, a large number of cells will be merged, and vice versa, they will remain fine with severe variability. Bandwidth variation can be effective in upscaling results. Therefore, determining the optimal bandwidth in this method is essential. For each bandwidth, the upscaled model has a number of upscaled blocks and an upscaling error. Obviously, higher thresholds or bandwidths cause a lower number of upscaled blocks and a higher sum of squares error (SSE). On the other hand, using the smallest bandwidth, the upscaled model will remain in a fine scale, and there will be practically no upscaling. In this work, different approaches are used to determine the optimal bandwidth or threshold for upscaling. Investigation of SSE changes, the intersection of two charts, namely SSE and the number of upscaled block charts, and the changes of SSE values versus bandwidths, are among these approaches. In this particular case, if the goal of upscaling is to minimize the upscaling error, the intersection method will obtain a better result. Conversely, if the purpose of upscaling is computational cost reduction, the SSE variation approach will be more appropriate for the threshold setting.

Quantum Key Distribution and Chaos Bandwidth Effects on Impact Security of Quantum Communications

The influence of bias current on the bandwidth of chaotic signals in semiconductor lasers by optical feedback has been studied experimentally and numerically. The measured data reveal that the bandwidth increase when the system becomes chaotic and this chaotic signal has a broadband spectrum so it can be used as a carrier for the quantum key. Mixing chaotic signal and quantum key make a very small change in chaotic bandwidth that does not affect the security of data transmitted.

Feature extraction algorithm of a precession target based on a Doppler frequency profile of dual-aspect observation.

In ballistic missile defense, using precession parameters is an effective way to determine warheads from decoys. Due to the geometric theory of diffraction, the backscattered field from a smooth object for a microwave radar consists of contributions from only isolated scattering centers. Further, thanks to the short wavelength of the laser, the ladar could obtain complete Doppler information of illuminated parts of precessing targets. On the basis of modeling the observation geometry of a rotating target with precession, a novel method for extracting precession parameters using coherent ladar based on a Doppler frequency profile (DFP) of dual-view observation is first proposed, to the best of our knowledge. By analyzing the periodic changes of bandwidth of a cone-shaped precessing object, we indicate that the sequence of DFP bandwidth can be approximate to a sinusoid function, based on which the precession period can be obtained through sinusoidal fitting. The precession angle can be obtained by combining dual-aspect receiving observation. A laboratory experiment verified the effectiveness of the proposed algorithm, and the errors of extracted parameters are about 10%.

Raman band widths of anhydrite II reveal the burning history of high‐fired medieval gypsum mortars

AbstractWhen used as a mineral binder, gypsum is thermally dehydrated and mixed with water, resulting in a paste hardening in the backreaction to calcium sulphate dihydrate (CaSO4 · 2 H2O). Although nowadays mainly hemihydrate‐based (CaSO4 · ½ H2O) binders are employed, higher firing temperatures in medieval kilns yielded anhydrite II (CaSO4). Except for the discrimination of the metastable phases anhydrite III and I due to different crystal structures, variations within the production temperature range of anhydrite II (approximately 300 to 1180°C) were not analytically accessible until recently. This study describes the development of an analytical technique, which is based on steady changes of band widths in room‐temperature Raman spectra of anhydrite II as a function of burning temperature. Raman microspectroscopic mapping experiments enable to pinpoint individual unreacted grains of thermal anhydrite in mortars and to discriminate them from natural anhydrites originating from the raw gypsum. The determination of band full widths at half maximum of down to 3 cm−1 and differences between them of a few tenths of wavenumbers is not a trivial task. Thus, a focus of this work is on peak fitting and strategies for correction of instrument‐dependent band broadening, which is often neglected also beyond the field of mortar analysis. Including other potential influences on band widths, burning temperatures of 400 to 900°C can be retraced in high‐fired medieval gypsum mortars with an uncertainty of approximately ± 50 K, as demonstrated with sample material of a stucco sculpture dated around 1400.

Sustainability Subjects in University Education - Development of a Comprehensive Indicator System and Quantitative Analysis of Degree Programs at German Universities

A new comprehensive evaluation system presented here allows to compare and to quantify education for a sustainable development (ESD) in degree programs. The evaluation is based on a criteria system working with three hierarchic levels. The highest level considers a list of 35 indicator terms. Primarily, the two most popular undergraduate (bachelor’s) degree programs in Germany (mechanical engineering, ME, and business administration, BA) have been reviewed for ESD contents based on the new evaluation scheme. Additionally we reviewed and quantified ESD subjects and their temporal changes in the entire bandwidth of degree programs of a university (Umwelt-Campus Birkenfeld, University of Applied Sciences Trier), back to 1999. Moreover, a spot check on international ME and BA bachelor’s degree programs was performed. Through our reviews, we found a high number of elective classes dedicated to ESD particularly in BA bachelor programs. However, the percentage of compulsory classes related to ESD is relatively low with 5-6 % in both ME and BA programs, respectively. The spot check on degree programs outside Germany revealed similar results. Analysing the time trend at Umwelt-Campus Birkenfeld, a considerable share of ESD that was part of the original diploma degrees was moved to what are now master’s degrees.

Spectrum manipulation of a dual-stop-band meta material terahertz filter based on unit cell dimension changes

We numerically and experimentally proposed a dual-stop-band terahertz filter based on standard microelectronic fabrication method. The stop bands locate at 0.32 THz and 1.02 THz with 3 dB bandwidths of 0.26 THz and 0.55 THz, respectively. The resonance characteristics of the proposed device were discussed with the help of surface current maps and field density maps extracted from computer simulation software to better understand the working principle of the proposed device. On top of that, a total of seven devices with different dimensions were fabricated to fully discuss the dimension effects on the resonant frequency shift and bandwidth changes. This fabrication process is applicable for related integrated metamaterial devices and provides essential experiment evidences for effective ways of manipulating the transmission spectrum of the proposed filter.

Numerical investigation of spin excitations in a doped spin chain

We study the doping evolution of spin excitations in a 1D Hubbard model and its downfolded spin Hamiltonians, by using exact diagonalization combined with cluster perturbation theory. In all models, we observe hardening (softening) of spin excitations upon electron (hole) doping, which are reminiscent of recent experiments on 2D cuprate materials. We also find that the 3-site and even higher-order terms are crucial for the low-energy effective spin models to reproduce the magnetic spectra of doped Hubbard systems at a quantitative level. To interpret the numerical results, we further employ a strong coupling slave-boson mean-field theory. The mean-field theory provides an intuitive understanding of the overall compact support of dynamic spin structure factors, including the shift of zero-energy modes and change of spin excitation bandwidth with doping. Our results can serve as predictive benchmarks for future inelastic x-ray or neutron scattering experiments on doped 1D antiferromagnetic Mott insulators.

Parameters of Laser Diodes Radiation in Different Temperature Intervals

The article deals with experimental studies that have been carried out in order to examine the radiation characteristics of commercially available semiconductor laser diodes and to analyze the reasons that cause changes in the characteristics of laser radiation. The need for such studies is connected with the search for expanding the possibilities of using semiconductor lasers in various appliances and devices operating in different conditions. The article presents experimental study results of the features of laser diodes emission spectra made on the basis of AlGaInP solid quadruple solution in the temperature range (50-300) K. The influence of temperature on the characteristics of the radiation spectrum was studied. The temperature was stabilized in a Cryomech ST15 closed-cycle vacuum helium cryostat. The radiation spectrum was investigated using a MDR-23 monochromator with a CCD detector installed. It is shown that the spectral characteristics of the emission spectrum (the predominance of stimulated or induced radiation, the wavelength of the radiation) depend on the operating temperature of the laser diode. Information is obtained that in the temperature range (50-300) K certain processes take place in the semiconductor laser diode material that lead to a change in the width of the forbidden band by approximately (4.2-4.5) % of the value corresponding to a temperature of 50 K. Data is given that the the temperature coefficient value of the change in the forbidden band width varies in absolute magnitude in 2-3 times within the investigated temperature interval. The authors propose an experimental method for determining the ionization energies of exciton levels localized in the region of the p-n junction of a laser diode. This method can find practical application for quality control of material in the manufacture of semiconductor lasers. The advantage of the proposed method is that it provides information on the exciton spectrum of a laser diode material in the narrow zone of the p-n junction in which laser radiation is formed.

Noise-induced vocal plasticity in urban white-crowned sparrows does not involve adjustment of trill performance components

Background noise can interfere with acoustic communication and subsequently influence signaling behavior. Immediate signaling flexibility (ISF) is a context-dependent form of behavioral plasticity that allows animals to temporarily change their acoustic behavior in response to noise fluctuations and potentially improve the chances of successful communication in noisy environments. The adaptive value of ISF is ultimately contingent on the response of the intended receiver, and there are differential effects on receiver response depending on which signal component is modified. However, there is scant research on whether ISF involves modification of a signal component specifically linked to mate attraction or territory defense. Our study addresses this knowledge gap and provides important insight into whether males employ short-term signal modification in a manner that could affect mate pairing success in birds. Specifically, we explore the maladaptive potential of ISF in the San Francisco, California population of Zonotrichia leucophrys nuttalli by testing for changes in trill bandwidth and rate—the specific trill structure components known to influence the receiver’s perception of vocal performance in this species—before and during noise broadcast experiments. Although Zonotrichia leucophrys nuttalli are capable of ISF, we found no evidence that noise induces temporary adjustment of the trill structure traits used by receivers to assess vocal performance.

Temperature-independent chirped FBG pressure transducer with high sensitivity

High sensitivity pressure transducer is always in demand in many industrial applications. In this paper, a highly sensitive temperature discriminated pressure transducer based on the use of natural rubber diaphragm and chirped fibre Bragg grating (CFBG) is proposed and demonstrated. The sensing mechanism is based on the measurement of bandwidth change and total reflection power. Results showed that the use of rubber diaphragm enhanced the sensitivity, which was experimentally obtained at -276.7 pm/kPa. Furthermore, the pressure transducer was temperature insensitive and cost-effective due to the simple demodulation technique.

Temperature-insensitive pressure transducer based on reflected broadened spectrum with enhanced sensitivity

Pasting of half the grating of an FBG sensor on a natural rubber diaphragm was used to sense the pressure measurement. The pressure-induced strain on half of the grating resulted in bandwidth broadening. From the pressure range of 0 kPa to 20 kPa, the pressure sensitivity at 15 dB bandwidth changed was obtained at 77.7 pm/kPa with 99.94% of linearity. Through total reflected power monitoring via photodetector, the pressure transducer retrieved a sensitivity of 0.1686 dB m/kPa and evaded a complex demodulation technique. As a result of the temperature-independent bandwidth change, the pressure transducer was totally temperature insensitive.