Intrinsic noise reduction of a Gamma-ray Backscattering imaging device

Cells operate in noisy molecular environments via complex regulatory networks. It is possible to understand how molecular counts are related to noise in specific networks, but it is not generally clear how noise relates to network complexity, because different levels of complexity also imply different overall number of molecules. For a fixed function, does increased network complexity reduce noise, beyond the mere increase of overall molecular counts? If so, complexity could provide an advantage counteracting the costs involved in maintaining larger networks. For that purpose, we investigate how noise affects multistable systems, where a small amount of noise could lead to very different outcomes; thus we turn to biochemical switches. Our method for comparing networks of different structure and complexity is to place them in conditions where they produce exactly the same deterministic function. We are then in a good position to compare their noise characteristics relatively to their identical deterministic traces. We show that more complex networks are better at coping with both intrinsic and extrinsic noise. Intrinsic noise tends to decrease with complexity, and extrinsic noise tends to have less impact. Our findings suggest a new role for increased complexity in biological networks, at parity of function.

A silicon photomultiplier (SiPM) is considered a next generation photo-sensor for low-light applications. In this study, we propose and develop the general concept of a multipurpose submillimeter gamma-ray (MSG) imaging module that is applicable to most gamma-ray imaging devices. The main features of the MSG module are submillimeter intrinsic resolution, geometrically expandable structure, expandable data acquisition system, multi-energy capability and usability in intense magnetic fields. The elements of the gamma-ray detector are pixelated Ce:GAGG ( $31\times 31$ pixels, 0.8 mm pitch), a 1.5-mm acrylic light guide, and one SiPM array ( $8 \times 8$ pixels). The readout electronics are composed of a symmetric charge division resistive network, 16 channel preamplifiers, multiplexing amplifiers, and analog-to-digital converter (ADC) circuits. We use a subminiature field-programmable gate array (FPGA) board as a data acquisition system. To make the system more expandable, we apply a 10 GbE-based tree structure using a FPGA-based data acquisition board and switching hub. To verify multipurpose capabilities, the energy spectra and the flood images are obtained using Co-57, Na-22, and Cs-137 isotopes. We measure temperature characteristics of the detector module. A pinhole image is obtained to confirm high resolution property. The maximal data transfer rate that is measured using dummy gamma-ray event packets is 963.143 Mbps. This detector module can be applied to nuclear medicine imaging devices and radiation monitoring systems.

Experimental test of the background rejection, through imaging capability, of a highly segmented AGATA germanium detector

Superconducting qubits can be sensitive to energy deposits caused by cosmic rays and ambient radioactivity. While previous studies have explored correlated effects in time and space due to cosmic ray interactions, we present the first direct comparison of a transmon qubit’s performance measured at two distinct sites: the above-ground SQMS facility (Fermilab, US) and the deep-underground Gran Sasso Laboratory (Italy). Despite the stark difference in radiation levels, we observe a similar average qubit relaxation time of approximately 80 microseconds at both locations. To investigate radiation-induced events, we employ a fast decay detection protocol, comparing the relative rates of events between the two environments. Although intrinsic noise remains the dominant source of errors in superconducting qubits, our analysis revealed a significant excess of radiation-induced events for high-coherence transmon qubits operated above-ground. Finally, using γ -ray sources with increasing activity levels, we evaluate the qubit response in a controlled low-background environment.

This paper proposes a robust independent component analysis (ICA) approach for noise reduction. Noise reduction is a difficult problem in ICA model. In general signal processing applications, there is more than one interference signal which may have unknown characteristics. In these situations, traditional linear ICA may lead to poor results. Hence, noise reduction is preferred to be performed with nonlinear adaptive filtering. In this paper, a radial basis function network (RBFN) is employed to transform the observed signals into output space in a nonlinear manner. The weights of RBFN are updated by utilizing a modified fixed‐point algorithm. The proposed method has not only the capacity of recovering the mixed signals, but also reducing noise with unknown characteristics from observed signals. The simulation results and analysis show that the proposed algorithm is suitable for practical unsupervised noise reduction problem. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(3): 45–52, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10073

The paper presents a new method of prediction of the swash plate moment based on a complex simulation model of the rotating group of swash plate axial piston machines. Due to further important demands within the design of the next generation of displacement machines – the reduction of noise and an increase of efficiency – the optimization of pump and motor control becomes really difficult. The application of the computer aided design tool CASPAR, a simulation tool developed at the Technical University of Hamburg-Harburg for the design and optimization of swash plate axial piston machines, allows the calculation of swash plate moments dependent on time, design and operating parameters of the machine. Especially the valve plate design affects the generated swash plate moment. The paper presents results of a simulation study into the influence of swash plate moments on the valve plate design. The dependency on the instantaneous pressure behaviour in the displacement chamber is explained. The simulation results were compared with experimental results obtained by measurements of the instantaneous pressure behaviour in the displacement chamber for various valve plate designs.

Gene transcription is a noisy process carried out by the transcription machinery recruited to the promoter. Noise reduction is a fundamental requirement for reliable transcriptional responses which in turn are crucial for signal transduction. Compared with the relatively simple transcription initiation in prokaryotes, eukaryotic transcription is more complex partially owing to its additional reinitiation mechanism. By theoretical analysis, we showed that reinitiation reduces noise in eukaryotic transcription independent of the transcription level. Besides, a higher reinitiation rate enables a stable scaffold complex an advantage in noise reduction. Finally, we showed that the coupling between scaffold formation and transcription can further reduce transcription noise independent of the transcription level. Furthermore, compared with the reinitiation mechanism, the noise reduction effect of the coupling can be of more significance in the case that the transcription level is low and the intrinsic noise dominates. Our results uncover a mechanistic route which eukaryotes may use to facilitate a more reliable response in the noisy transcription process.

Noise reduction performance and maintenance time of porous asphalt pavement

In the present study has addressed the application of noise canceling FxAFA using dynamic step size algorithm, and we got the result that the noise reduction of FxAFA dynamic step size algorithms better then FxAFA algorithm. But when Compared with the noise reduction to FxLMS algorithms, FxLMS still better than the FxAFA dynamic step size algorithm. Based on the data from the computer simulation results of noise reduction FxLMS = 27.6793 dB, FxAFA dynamic step size and FxAFA db = 26.0329 = 23.6059 dB. Keywords: FxAFA, FxAFA dynamic adaptation measures, noise removal

This paper investigates how ground bounce noise (GBN) is generated by crosstalk noises for two parallel ground planes with a narrow open-stub line (NOSL) and adjacent signal traces in a multilayer package structure. A noise reduction scheme and design guidelines for preventing intense noises (GBN and coupled noise) are also proposed. A graphical method that is based on wave tracing is also developed to elucidate the generation of crosstalk noise by adjacent signal traces on an NOSL. The mechanism of generation of the GBN by crosstalk noise can be elucidated based on reflection theory, open-stub quarter-wavelength resonance, and parallel-plane resonance. The time-domain simulation results are analyzed using a 3-D full-wave simulator, Computer Simulation Technology. Using an additional shorting via at the connection between the NOSL and parallel ground planes, the proposed noise reduction scheme can significantly reduce the GBN and coupled noise. Moreover, guidelines for designing the test structure to minimize noise (GBN and coupled noise) are presented. Finally, the simulation and measurement results in the time domain are compared to validate the proposed analysis and noise reduction scheme.

For greater advancement in future communication, efficient noise reduction algorithms with lesser complexity are a necessity. Noise in audio signal poses a great challenge in speech recognition, speech communication, speech enhancement and transmission. Hence the most efficient algorithm for noise reduction must be chosen in such a way that the cost for noise removal is a less as possible, but a large portion of noise is removed. The common method for the removal of noise is optimal linear filtering method, and some algorithms in this method are Wiener filtering, Kalman filtering and spectral subtraction technique. Here, the noise signal is passed through a filter or transformation. However, due to the complexity of these algorithms, there are better algorithms like Signal Dependent Rank Order Mean algorithm (SD-ROM), which removes noise from audio signals and retains the characteristics of the signal. The algorithm can be adjusted depending on the characteristics of noise signal too. To remove white Gaussian noise, discrete wavelet transform technique is used. After each of the techniques are applied to the samples, SNR and elapsed time are calculated. All of the above techniques show an increased Signal to Noise Ratio (SNR) after processing, as seen in the simulation results.

Cemented carbide circular saw blades are widely used for wood cutting, but they often suffer from vibration and noise issues. This study presents a multi-objective optimization method that integrates ANSYS and MATLAB to optimize the design of noise reduction slots in circular saw blades. A mathematical model was developed to correlate the emitted sound power with the overall vibration intensity. A multi-objective optimization model was then formulated to map the slot shape parameters to the deformation, equivalent stress, and vibration intensity during sawing. The ABAQUS thermal–mechanical coupling analysis was used to determine the sawing force and temperature field. The NSGA-II algorithm was applied on the ANSYS–MATLAB platform to iteratively compute slot shape parameters and conduct optimization searches for a globally optimal solution. Circular saw blades were fabricated based on the optimization results, and experimental results showed a significant reduction in sawing noise by 2.4 dB to 3.0 dB on average. The noise reduction effect within the specified frequency range closely agreed with the simulation results, validating the method’s efficiency. This study provides a feasible and cost-effective solution to the multi-objective optimization design problem of noise reduction slots for circular saw blades.

Edge noise is generated if turbulence interacts with solid edges. Reduction of trailing edge noise of airfoils can be achieved by replacing the solid material at the trailing edge by inlays of porous permeable material. The acoustic benefit of approximately 6 dB of such treatment is known from experiments. Enroute to numerically optimized porous properties, this paper presents a first principle based Computational Aeroacoustics (CAA) method for predicting the acoustic effect of a porous NACA0012 trailing edge. In a hybrid two-step CFD/CAA procedure the turbulence statistics from a solution of the Volume Averaged Navier-Stokes (VANS) equations is used as a basis for the prediction of turbulent-boundary-layer trailing-edge noise (TBL-TEN). For the acoustic part of the calculation, the Acoustic Perturbation Equations (APE) are solved in the flow field. Inside the porous regions, a different set of governing equations, referred to as Linear Perturbation Equations (LPE) will be solved. The LPE represent a modified form of the Linearized Euler Equations (LEE) with the APE vorticity source term shifted to the right-hand side. The new set of equations is derived by volume averaging the Navier-Stokes equations and decomposing the flow variables into a time-averaged mean part and a fluctuating part and isolating the vorticity source term to the right-hand side of the momentum equation. The LPE are verified by an analytical solution. The simulation results of a NACA0012 airfoil geometry with and without porous trailing edge treatment are compared to wind tunnel measurements. The noise reduction effect of such a trailing edge treatment is successfully demonstrated.

The serration assembly installed at the trailing-edge of wind turbines can reduce the turbulent boundary-layer trailing-edge noise. This work studies the aeroacoustic response and noise reduction capability of four different trailing-edge serrations, involving a novel Multi-Flapped-Serration with Iron-Shaped Edges (MFS-Iron) presented here. These four serrations are retrofitted to S809 and NACA643418 airfoils. The Large-eddy simulation (LES) method and Ffowcs Williams and Hawkings integration (FW-H) methods are respectively employed to predict the unsteady flow field and far-field noise based on optimized structured and unstructured hybrid grids. From the numerical simulation results, we explore the trailing-edge noise reduction mechanism. The results show that the proposed MFS-Iron can effectively realize noise reduction under appropriate design parameters and optimize the aerodynamic layout. When using the MFS-Iron serration, the cross-flow intensity between the serration gap is significantly reduced, and the original two groups of symmetrical horseshoe vortex are mixed into a single vortex, which has a positive impact on the suppression of high-frequency noise. By further studying the Lamb vector divergence vortex dynamics process near the surface of serrated trailing-edge, it is found that the Lamb vector divergence is directly related to the intensity of the noise source.

Random pulse width modulation (RPWM) is a switching technique used to spread voltage and current harmonics over a wide frequency range. By using a randomly changing inverter switching frequency, the power spectrum of the electromagnetic acoustic noise can be spread to the wideband area. Wideband noise is much more comfortable and less annoying than narrowband noise. Thus, RPWM has been attracting interest as an excellent method for the reduction of acoustic noise in inverter drive systems. A new RPPWM (random position space vector PWM) is proposed and implemented. Each of three phase pulses is located randomly in each switching interval. Along with randomisation of the PWM pulses, space vector modulation is also executed in a C167 microcontroller. Simulation and experimental results show that the voltage and current harmonics are spread to the wideband area and that the audible switching noise is reduced by using the proposed RPPWM method.