Peak Noise Research Articles

Active Shielding of MWCNT Bundle Interconnects: An Efficient Approach to Cancellation of Crosstalk-Induced Functional Failures in Ternary Logic

This study presents an efficient geometry for active shielding of multiwalled carbon nanotube (MWCNT) bundle interconnects which cancels the crosstalk-induced functional failures in ternary logic. In this geometry, MWCNT bundles are used innovatively as shields on both sides of the signal transmission line to reduce the crosstalk effects while maintaining the minimum interconnect pitch. Simulations are performed using HSPICE for intermediate and global interconnects in ternary logic at 14-nm node. The results indicate that the crosstalk-induced functional failure in ternary logic is omitted by using the proposed structure. Moreover, according to the results, our proposed geometry reduces the crosstalk noise peak as compared to the widened MWCNT bundles, distanced MWCNT bundles and Cu interconnects on average by 41%, 44%, and 61% for the intermediate interconnects and 61%, 46%, and 74% for the global interconnects, respectively, without any considerable power consumption penalties.

Electron-Phonon Coupling as the Source of 1/f Noise in Carbon Soot

Two 1/f noise peaks were found in a carbon soot resistor at voltages characteristic of Kohn anomalies in graphite. The ratio of the electron-phonon coupling matrix elements at the anomalies calculated from the noise peak intensities is the same as the one obtained from the Raman frequencies. This demonstrates that the electron-phonon coupling is the microscopic source of 1/f noise in carbon soot. A new, very general formula was deduced for the frequency exponent, wherein nonlinearity and dispersion are the only ingredients. The interplay between nonlinearity and dispersion in this formula describes the sublinear-supralinear transitions experimentally observed at both anomalies in the voltage dependence of the frequency exponent. A quadratic dependence of the 1/f noise parameter on the matrix element is proposed and applied to explain the M-shape of the 1/f noise in graphene. We found that the frequency exponent mimics the dependence of the noise intensity in the whole voltage range, while both are the image of the graphite phonon spectrum. This implies that the source of nonlinearity is in the electron-phonon coupling which modulates the slope of the spectrum. It requires the presence of 1/f noise in the thermal noise background of the resistor till phonon frequencies.

In-vehicle noise exposure among military personnel depending on type of vehicle, riding compartment and road surface

IntroductionNoise-induced hearing loss is one of the most common health problems among military service personnel. Exposure to noise in military vehicles constitutes a large proportion of total noise exposure. This...

Evaluation of Hamamatsu PET imaging modules for dedicated TOF-capable scanners.

Time-of-flight (TOF) capability is becoming an important capability offered in both commercial and research PET scanners. Often commercial vendors and laboratory researchers develop and utilize proprietary electronics for their devices. Consequently, it is challenging for independent research groups to develop their own TOF-PET scanners. In this investigation, we tested a prototype scanner consisting of commercially available TOF-capable modules from Hamamatsu Photonics that can be used as building blocks for PET scanners. The scanner consists of a ring of 16 modules, for a total diameter of 26.7 cm. Testing demonstrated that the scanner is capable of sustaining ~1 MHz single counting rate with a peak noise equivalent count rate (NECR) of 117.5 kHz at 75.25 MBq measured with NEMA NU-4 "rat" phantom. Spatial resolution of 2.3 mm 5 mm from the center of the scanner was measured. Energy resolution of 17.2% at 511 keV was measured. Peak sensitivity of 1.28% is reported. All the measurements were performed with energy cuts from 350 to 700 keV Finally, scanner timing resolution was found to be 462 ps. Results from testing of a prototype scanner constructed using newly released TOF-capable detector modules produced by Hamamatsu demonstrated the promise for these devices to create high performance PET system with TOF capabilities.

Adaptive signal enhancement for overlapped peaks based on weighting factor selection

Peak-sharpening is an effective method for the peak position detection of overlapped spectra. However, the weighing factor parameter strongly affects the sharpening performance, and the derivative adopted in the peak-sharpening method is sensitive to noise. In this paper, an adaptive peak-sharpening method based on weighting factor selection is proposed. The relationship between the sharpening ratio and weighting factor is studied. In addition, the Savitzky–Golay filter is adopted due to its excellent noise reduction and peak shape retention abilities. First, the smoothed signal and second-order derivative signal are obtained by the Savitzky–Golay filter. Then, the parameters of the overlapped peaks are estimated for the weighting factor selection. Next, the peak position is detected by the peak-sharpening method. After that step, the estimated parameters are updated, and the above steps are iterated until the detection of the peak position converges. Finally, the converged results are considered to be the final detection results. The experimental results using a simulated dataset, a virtual mass spectra dataset and a polarography dataset show that the proposed method is effective for peak position detection.

Study of ECG Signals based on Gender and Heart Abnormalities

Appropriate QRS detection of the ECG signal is extremely important for determining the variations in the heart rate. The two most famous algorithms for the QRS detection are Murthy and Rangaraj and Pan and Tompkin. Using these two algorithms, comparison of results for five different datasets i.e., MIT-BIH arrhythmia database, European ST-T database, the MIT-BIH Noise stress test database, the BIDMC congestive heart failure database and intracardiac atrial fibrillation database was done in MATLAB and comparative analysis was obtained on the basis of age, sex and heart rate (above 95 and below 60). Murthy and Rangaraj algorithm is the methodology which is derivative-based and provides results without any delay and gives reduced noise and sharp peak output. On the other hand, Pan and Tompkin algorithm performs the analysis of slope, width and amplitude of QRS complexes and is found to have higher accuracy than other real-time methods.

A GIS – based method for assessment and mapping of noise pollution in Ota metropolis, Nigeria

A detailed method used for assessing and mapping noise pollution levels in Ota metropolis, Nigeria using ArcGIS 10.5 Software is presented in this paper. Noise readings were measured at a time interval of 30 min for each site considered using a precision grade sound level meter. The noise map developed was based on the computed values of average equivalent noise (LAeq) for the selected locations. Results of this study show that the A weighted sound level (LAeq), the background noise level (L10) and the peak noise level (L90) vary with location and period of the day due to traffic characteristics especially traffic volume, vehicle horns, vehicle mounted speakers, and unmuffled vehicles at road Junctions, major roads, motor parks and commercial centres. Based on the U.S. Department of Housing and Urban Development (HUD) recommendations and standards, only one (1) out of the 41 locations considered is under normally acceptable situation, while 12 locations are under normally unacceptable and the noise levels of the rest locations are clearly unacceptable. Results of this study are useful as reference and guideline for future planning and regulations on noise limit to be implemented for urban areas like Ota Metropolis.•Instrumentation used in this study for the environmental noise measurements consisted of a precision-grade sound-level meter – Model 8922 RS232.•The Geographical Positioning System (GPS) device (model: Magellan eXplorist 310) was used to obtain the exact coordinates of each location where noise level readings were recorded.•ArcGIS 10.5 software was used in this study to develop noise map for Ota Metropolis.

Comparative Analysis of Simultaneous Switching Noise Effects in MWCNT Bundle and Cu Power Interconnects in CNTFET-Based Ternary Circuits

In this paper, the impacts of the simultaneous switching noise (SSN) in carbon nanotube field effect transistor-based ternary circuits are investigated. These effects, including the peak noise on the $V_{\mathrm {DD}}$ and ground rails and the SSN-induced delay and output noise are compared between traditional Cu and multiwall carbon nanotube bundle power interconnects in ternary circuits. Simulations are performed using HSPICE for global power interconnects at 14- and 7-nm technology nodes. The results indicate that for interconnects with 200- $\mu \text{m}$ length, the peak SSN voltage on the $V_{\mathrm {DD}}$ and ground rails for a power distribution network, including ten ternary buffers, using multi-walled carbon nanotube (MWCNT) bundle power interconnects is 53% and 40% lower, respectively, compared to Cu power interconnects in the last stage at the 14-nm node. Also, with scaling down the technology to 7 nm, these improvements increase to 60% and 59%, respectively. Moreover, MWCNT bundle power interconnects reduce the SSN-induced delay at the output of the tenth stage for interconnects with 200- $\mu \text{m}$ length on average by 82% as compared to the Cu interconnects at the 14-nm node. This improvement is 73% for the 7-nm technology node.

Noise Exposure on Mixed Grain and Livestock Farms in Western Australia

Noise presents an ongoing occupational health and safety issue, which despite numerous studies still presents a significant risk in agriculture with high exposures prevalent. In this study, we measured noise exposures associated with significant activities on 42 mixed grain and livestock farms in Western Australia. Employing a mixture of personal noise measurements using dosimeters, noise measurements using sound level meters, and a validated survey, we identified that 32% of farm workers were exposed to noise levels above the LAeq,8h 85 dB(A) limit, before considering extended shifts. We also noted that extended shift lengths, of up to 16 h in some cases, were possible. In addition, we found that 37% of workers were exposed to noise peak of 140 dB(C) or greater. It was further noted that hearing protection is not typically worn for the duration of an activity and is only for a small number of tasks. However we did find some evidence that farmers had begun to implement some form of noise management practice, usually in the form of buying quieter equipment or separating noisy tasks from quiet tasks. Improved education for farmer and farm workers in terms of the risks posed by noise, identifying noisy tasks, is recommended, as well as a programme to encourage better and consistent use of hearing protection.

Narrow-linewidth swept laser phase reconstruction and noise measurement technology and its applications.

A dynamic noise characterization technique for measuring narrow-linewidth frequency-sweep lasers based on phase reconstruction method is proposed. The phase and the frequency fluctuation power spectral density (PSD) of the swept optical field within a specific time window are recovered mainly by demodulating the differential phase information of the 120-degree phase difference interferometer. Then the details of the laser noise characteristics and the performance evolution law of the frequency sweep process can be observed by investigating the calculated frequency fluctuation PSD. Moreover, the integration time linewidth and Lorentzian linewidth of the swept frequency field can be obtained by introducing the integral algorithm even beyond the limit of PSD physical resolution. Meanwhile, the power of this method is verified by applying it to a kHz-linewidth frequency swept laser source based on high-order modulation-sideband injection-locking. The results show many features of the laser such as specific noise peaks and the laser characteristic evolution rules which could not be measured by other traditional methods.

Combustion instability effect on sound generation by jet diffusion flame

This paper presented a numerical study of flow instability effects on the sound generation by jet diffusion flames. Numerical simulation coupled with the acoustic analogy based on Lilley’s equation was employed to predict the sound radiation. A parametric study by varying the Froude number was carried out, and simulations were performed with different levels of external forcing to shed light on the competing acoustic responses of the buoyant and jet preferred instabilities. The detailed sound source structure was provided by the flow details. It is shown that the increase of buoyancy is responsible for the development of the acoustic source in the downstream flame region. When the Froude number is larger than unity, only low-frequency noise will be affected, and when the Froude number is less than unity, combustion-induced buoyancy has a further positive impact on the noise level in the high-frequency region. The jet preferred instability caused by external disturbance can improve the intensity of the sound source and may further be amplified as the noise peak, depending on the buoyancy level. An acoustic transfer function was therefore analyzed to characterize the different acoustic responses. The results showed that there is a positive correlation between the buoyancy level and the acoustical response rate of external disturbance, and the high-frequency disturbance is much easier to be amplified by flame than that with low frequency, especially in the downstream flow field.

Performance evaluation of the next generation solid-state digital photon counting PET/CT system

BackgroundThe first solid-state silicon photomultiplier (SiPM) digital photon counting (DPC) clinical PET/CT system was introduced by Philips in recent years. The system differs from other SiPM-based PET/CT systems and uses lutetiumyttrium oxyorthosilicate (LYSO) scintillators directly coupled with their own individual SiPM DPC detectors eliminating the need for Anger-logic positioning decoding. We evaluated the system performance, characteristics, and stability of the next generation DPC clinical PET/CT based on NEMA NU2-2012 tests, NEMA NU2-2018 test (timing resolution) and human studies.ResultsAn energy resolution of 11.2% was measured. NEMA NU2-2012 tests revealed a spatial resolution (mm in FWHM) from (3.96, 4.01, 4.01) at 1 cm to (5.81, 5.83, 4.95) at 20 cm for (axial, radial, tangential). A 5.7 cps/kBq system sensitivity was measured. Peak noise equivalent count rate (NECR) and peak true count rate could not be determined as each exhibited increasing values up to the maximum activity measured (~ 1100 MBq). The maximum NECR was 171 kcps @ 50.5 kBq/mL, with corresponding scatter fraction of 30.8% and maximum trues of 681 kcps. NEMA hot sphere contrast ranged from 62% (10 mm) to 88% (22 mm), cold sphere contrast of 86% (28 mm) and 89% (37 mm). A timing resolution of 322 ps (22Na point source based) and 332 ps (NEMA NU2-2018) was obtained. It revealed < 1% change in TOF timing and ± 0.4% change in energy resolution during 31-month stability monitoring. CQIE assessment found < 3% axial variance in SUV. 100–60% recovery coefficients of activity concentration at various sphere sizes and contrast levels were measured.ConclusionsThis scanner represents the first solid-state DPC PET/CT, a technologic leap beyond photomultipliers tubes and anger logic. It presents considerable improvements in system performance and characteristics with excellent time-of-flight capability compared to conventional photomultiplier tube (PMT) PET/CT systems. The DPC system leads to promising clinical opportunities with excellent image quality, lesion detectability, and diagnostic confidence.

Noise Exposure and Self-reported Hearing Impairment among Gas-fired Electric Plant Workers in Tanzania.

Background:Gas-fired electric plants are equipped with heavy machines, which produce hazards including noise pollution. Exposure to high level of noise of above 85dB(A) is known to bring about Noise-Induced Hearing Loss (NIHL). This study aimed to assess noise exposure level and reported prevalence of noise-induced hearing loss among workers in gas-fired electric plants.Material and Methods:This cross-sectional study was conducted in three gas-fired electric plants in Dar es Salaam (Plant A, Plant B and Plant C) from July to August 2017. A noise logging dosimeter was used to measure personal noise exposure level. A questionnaire was used to collect information on managerial factors, individual factors, socio-demographic factors and history of the participants. A short screening validated questionnaire was used to obtain noise exposure score. Frequency distribution, Chi-square test and Regression analyses were done using SPSS version 20.Results:One hundred and six participants were involved in the study. Noise exposure level among gas-fired electric plant workers was above 85dB(A), n = 37. The equivalent sound level (LAeq) measured over 8 hours was (98.6 ± 9.7) dB(A). The mean noise peak level was (139.5 ± 9.4) dB(A). Plant C had higher mean noise exposure level (TWA) of (96.9 ± 5.1) dB(A) compared to plant B 96.4 ± 3.7dB(A) and plant A 78.7 ± 11.9dB(A). Participants in both operation and maintenance had higher equivalent sound level (LAeq) measured over eight hours of 101.980 ± 3.6dB(A) compared to maintenance alone 98.5 ± 12.4dB (A) or operation 97.7 ± 8.8dB (A). Proportion of participants with reported hearing loss was 57(53.8%) where 44(41.5%) participants reported difficulty hearing people during conversations. Hearing protective devices (HPDs) were reported to be used by a majority, 101(95.3%).Conclusion:Workers in gas-fired plants are exposed to high noise levels that could damage their hearing. Hearing conservation programs should be established and maintained in this work environment.

Effect of Noise on Moving Cut Data-Permutation Entropy

The effect of peak noise and white Gaussian noise on moving cut data-permutation entropy method is discussed by constructing the nonlinear ideal time series. The results show that the moving cut data-permutation entropy method can accurately detect the location of the mutational point, even if the time series with high noise level, which showed that the effect of peak noise and white Gaussian noise on the result of this method is small. The moving cut data-permutation entropy has strong anti-noise ability, which is beneficial to the application of this method in actual observation data.

Low-noise structure optimization of a heavy commercial vehicle cab based on approximation model

Structure design for reducing noise is essential and widely studied because cab interior noise seriously affects the ride comfort of the driver and passengers, especially for heavy commercial vehicles. This paper proposes an enhancement investigation on the low-noise structure performance of a cab in a heavy commercial vehicle based on an approximation model. A series of vibroacoustic tests with varying running speeds are implemented first to acquire the vibration signals at four cab suspensions and the sound pressure signal at the right ear of the driver. The finite element model and structure–acoustic coupled model of the cab of a heavy commercial vehicle are established sequentially. When the vibration accelerations measured in the tests are converted into excitation signals using the cab structure–acoustic coupled model, the sound pressure of the right ear of the driver is predicted, and the accuracy of the cab structure–acoustic coupled model is then verified. After panel acoustic contribution analysis, an approximation model of critical panel thickness and the peak noise near the right ear of the driver is established in accordance with the radial basis function. Genetic algorithm is utilized to solve an optimization model to obtain optimal panel thicknesses. By comparing the right ear sound pressure before and after optimization, the results confirm that optimized panel thicknesses can reduce sound pressure level of the critical frequency.

Small animal, positron emission tomography-magnetic resonance imaging system based on a clinical magnetic resonance imaging scanner: evaluation of basic imaging performance.

Development of advanced preclinical imaging techniques has had an important impact on the field of biomedical research, with positron emission tomography (PET) imaging the most mature of these efforts. Developers of preclinical PET scanners have joined the recent multimodality imaging trend by combining PET imaging with other modalities, such as magnetic resonance imaging (MRI). Our group has developed a combined PET-MRI insert for the imaging of animals up to the size of rats in a clinical 3T MRI scanner. The system utilizes a sequential scanner configuration instead of the more common coplanar geometry. The PET component of the system consists of a ring of 12 liquid-cooled, SiPM-based detector modules ( ). System performance was evaluated with the NEMA NU 4-2008 protocol. Spatial resolution is 5cm from the center of the field-of-view measured from single-slice rebinned filtered backprojection-reconstructed images. Peak noise equivalent count rate is 17.7kcps at 8.5MBq; peak sensitivity is 2.9%. The MRI component of the system is composed of a 12-cm-diameter birdcage transmit/receive coil with a dual-preamplifier interface possessing very low noise preamplifiers. System performance was evaluated using American College of Radiology-based methods. Image homogeneity is 99%; the ghosting ratio is 0.0054. The signal-to-noise ratio is 95 and spatial resolution is . There was no discernable cross-modality interference.

Improving visualization of trace components for quantification using a power law based integration approach

In some cases, trace component analysis only requires a sensitive and high-resolution mass spectrometer. However, enantiomers must be completely separated to be differentiated with a mass spectrometer, which is highly dependent on the stationary-mobile phase composition. In case of a challenging chiral separation, instead of trying new columns for screening purpose, resolution enhancement techniques could be used to resolve partially overlapping peaks. A well-known enhancement method is the power law, which increases the linear dynamic range of each analyte and reduces excessive noise. In many cases, the peak noise can decrease significantly by applying the power law. However, the main drawback is that this approach changes relative peak areas and heights of each peak in a non-linear fashion which limits its use for quantitative purposes. In this study, a normalized power law was utilized for extracting correct area information. It is a simple (5 step) protocol that only requires Microsoft Excel, and results in enhanced visualization of trace components, especially in low signal/noise environments, and makes integration convenient and reproducible. Several difficult chiral trace component analyses were investigated, including applications pertaining to ultrafast high-throughput chromatography, enantiopurity, and peak purity analysis. For complicated cases with multiple overlapped peaks of different resolutions, a segmented normalized power law was utilized. A trace component coeluting near a dead volume peak and a trace enantiomeric component in the tail of the corresponding enantiomeric peak were virtually enhanced. As an additional tool, first and second derivatives were utilized to identify if an enantiomeric impurity is coeluting with the dominant enantiomer under overload conditions. Idiosyncrasies of the derivative test are discussed. This study shows how these simple approaches can be used for accurate quantitation, specifically for trace enantiomeric components.

Study of the characteristics and suppression of EMI of inverter with SiC and Si devices

The paper systematically studies the impacts of two major factors: device switching actions and inverter switching frequency on the whole EMI spectrum. Several powerful experimental results of electromagnetic interference(EMI) in voltage source inverter(VSI) with SiC and Si devices are provided. As far as the influence of switching actions is concerned: faster switching speed will generate higher EMI noise levels in the high frequency range, and ringing in the device switching will also make the EMI noise near the ringing frequency range worse. In the meantime, increasing of the switching frequency of the inverter will result in a higher EMI noise peak for the whole EMI spectrum. In order to suppress the EMI noise of the converter to meet standards, Random PWM(RPWM) and EMI filters are adopted. With RPWM, the EMI current can drop a few more dB than that with SVPWM, which makes the filter work better. Also, as extra attenuation can be provided, it provides the benefit of reducing the weight and volume of the inductor of the filter. Therefore, the combination of an advanced modulation strategy and EMI filter is proposed for suppressing of EMI noise in an inverter.

Performance Analysis of Lossy Coupled Non-uniform On-Chip Interconnects with Skin Effects

This paper presents an accurate numerical model to evaluate the propagation delay and crosstalk noise of high-speed on-chip interconnects. The structure of on-chip interconnect is considered as non-uniform, including the skin effects. The lossy coupled non-uniform interconnects are modelled by finite-difference time-domain technique. For accurate performance analysis, nonlinear complementary metal–oxide–semiconductor is used to drive the interconnect lines. The nonlinear effects are also incorporated in the proposed model using the improved alpha power law model. The propagation delay and peak noise voltage on the victim line in dynamic and functional switching conditions are analysed and validated with Hailey simulation program with integrated circuit (HSPICE) simulations. The proposed model accuracy and computational efficiency are compared with HSPICE simulations for different cases. The comparison results show that the average error is less than 0.6% while estimating the peak noise voltage using HSPICE. Moreover, the proposed model shows a 75.2% reduction in average CPU runtime compared with HSPICE simulations. Therefore, the proposed model is fast and accurate in predicting the crosstalk-induced performance analysis of lossy coupled non-uniform interconnects at high frequencies.

Pneumatic rock drill vs. electric rotary hammer drill: Productivity, vibration, dust, and noise when drilling into concrete

ObjectivesBoth pneumatic rock drills and electric rotary hammer drills are used for drilling large holes (e.g., 10–20 mm diameter) into concrete for structural upgrades to buildings, highways, bridges, and airport tarmacs. However, little is known about the differences in productivity, and exposures to noise, handle vibration, and dust between the two types of drills. The aim of this study was to compare these outcomes with similar mass electric rotary and pneumatic rock drills drilling into concrete block on a test bench system. MethodThree experiments were conducted on a test bench system to compare an electric (8.3 kg) and pneumatic drill (8.6 kg) on (1) noise and handle vibration, (2) respirable silica dust, and (3) drilling productivity. The test bench system repeatedly drilled 19 mm diameter x 100 mm depth holes into cured concrete block while the respective exposure levels were measured following ISO standards. ResultsProductivity levels were similar between the electric and the pneumatic drill (9.09 mm/s vs. 8.69 mm/s ROP; p = 0.15). However, peak noise (LPeak: 117.7 vs. 139.4 dBC; p = 0.001), weighted total handle vibration (ahw: 7.15 vs. 39.14 m/s2; p = 0.002), and respirable silica dust levels (0.55 vs. 22.23 mg/m3; p = 0.003) were significantly lower for the electric than the pneumatic drill. DiscussionWhile there were no differences in drilling productivity between an electric and pneumatic drill of similar mass, there were substantial differences in exposure levels of noise, handle vibration, and respirable silica dust. Structural contractors should switch from pneumatic rock drills to electric rotary hammer drills for structural drilling into concrete in order to reduce worker exposures to the hazards of noise, hand vibration, and silica dust.