Entropic stochastic resonance induced by a transverse driving force

The phenomenon of entropic stochastic resonance (ESR) is investigated with the presence of a time-periodic force in the transverse direction. Simulation results manifest that the ESR can survive even if there is no static bias force in any direction, just if a transverse driving field is applied. In the weak noise region, the transverse driving force leads to a giant-suppression of the escape rate from one well to another, i.e. the entropic trapping. The increase in noise intensity will eliminate this suppression and induce the ESR phenomenon. An alternative quantity, called the mean free flying time, is also proposed to characterize the ESR as well as the conventional spectral power amplification. The ESR can be modulated conveniently by the transverse periodic force, which implies an alternative method for controlling the dynamics of small-scale systems. This article is part of the theme issue ‘Vibrational and stochastic resonance in driven nonlinear systems (part 2)’.

Deep Boltzmann Machines: Rigorous Results at Arbitrary Depth

A class of deep Boltzmann machines is considered in the simplified framework of a quenched system with Gaussian noise and independent entries. The quenched pressure of a K-layers spin glass model is studied allowing interactions only among consecutive layers. A lower bound for the pressure is found in terms of a convex combination of K Sherrington–Kirkpatrick models and used to study the annealed and replica symmetric regimes of the system. A map with a one-dimensional monomer–dimer system is identified and used to rigorously control the annealed region at arbitrary depth K with the methods introduced by Heilmann and Lieb. The compression of this high-noise region displays a remarkable phenomenon of localisation of the processing layers. Furthermore, a replica symmetric lower bound for the limiting quenched pressure of the model is obtained in a suitable region of the parameters and the replica symmetric pressure is proved to have a unique stationary point.

A New Filtering System for Using a Consumer Depth Camera at Close Range

Using consumer depth cameras at close range yields a higher surface resolution of the object, but this makes more serious noises. This form of noise tends to be located at or on the edge of the realistic surface over a large area, which is an obstacle for real-time applications that do not rely on point cloud post-processing. In order to fill this gap, by analyzing the noise region based on position and shape, we proposed a composite filtering system for using consumer depth cameras at close range. The system consists of three main modules that are used to eliminate different types of noise areas. Taking the human hand depth image as an example, the proposed filtering system can eliminate most of the noise areas. All algorithms in the system are not based on window smoothing and are accelerated by the GPU. By using Kinect v2 and SR300, a large number of contrast experiments show that the system can get good results and has extremely high real-time performance, which can be used as a pre-step for real-time human-computer interaction, real-time 3D reconstruction, and further filtering.

Detection of Defects Using Spatial Variances of Guided-Wave Modes in Testing of Pipes

In the past decade, guided-wave testing has attracted the attention of the non-destructive testing industry for pipeline inspections. This technology enables the long-range assessment of pipelines’ integrity, which significantly reduces the expenditure of testing in terms of cost and time. Guided-wave testing collars consist of several linearly placed arrays of transducers around the circumference of the pipe, which are called rings, and can generate unidirectional axisymmetric elastic waves. The current propagation routine of the device generates a single time-domain signal by doing a phase-delayed summation of each array element. The segments where the energy of the signal is above the local noise region are reported as anomalies by the inspectors. Nonetheless, the main goal of guided-wave inspection is the detection of axisymmetric waves generated by the features within the pipes. In this paper, instead of processing a single signal obtained from the general propagation routine, we propose to process signals that are directly obtained from all of the array elements. We designed an axisymmetric wave detection algorithm, which is validated by laboratory trials on real-pipe data with two defects on different locations with varying cross-sectional area (CSA) sizes of 2% and 3% for the first defect, and 4% and 5% for the second defect. The results enabled the detection of defects with low signal-to-noise ratios (SNR), which were almost buried in the noise level. These results are reported with regard to the three different developed methods with varying excitation frequencies of 30 kHz, 34 kHz, and 37 kHz. The tests demonstrated the advantage of using the information received from all of the elements rather than a single signal.

KLASIFIKASI BIT-PLANE NOISE PADA GAMBAR MENGGUNAKAN LOGIKA FUZZY

Teknik steganografi BPCS (Bit-Plane Complexity Segmentation) merupakan salah satu teknik steganografi yang cukup baru. Salah satu proses penting dalam Teknik Steganografi BPCS adalah proses penghitungan nilai kompleksitas suatu bit-plane. Nilai kompleksitas dihitung dengan melihat seberapa banyak pergantian bit yang terdapat dalam sebuah bit-plane. Jika bit-plane tersebut memiliki nilai kompleksitas yang tinggi, maka bi-plane tersebut dikategorikan sebagai bit-plane noise yang tidak mengandung informasi yang berharga pada gambar. Klasifikasi bit-plane yang menggunakan himpunan cripst (noise dan tidak) tersebut tidak adil, dimana sebuah perbedaaan nilai yang sedikit saja akan mengubah secara signifikan status dari bit-plane tersebut. Penelitian ini mencoba untuk menerapkan prinsip himpunan fuzzy untuk mengklasifikasikan bit-plane menjadi kedalam tiga buah himpunan yaitu informatif, informatif sebagian, dan noise region. Klasifikasi bit-plane kedalam himpunan fuzzy terebut diharapkan dapat menggolongkan bit-plane secara lebih objektif dan pada akhirnya daya tampung gambar terhadap pesan dapat ditingkatkan dengan dengan menggunakan inferensi fuzzy mamdani untuk mengambil keputusan bit-plane mana yang akan digantikan dengan pesan berdasarkan klasfikasi bit-plane yang tersedia dan ukuran pesan yang akan disisipkan.

Reproducibility of SELDI Spectra across Time and Laboratories

The reproducibility of mass spectrometry (MS) data collected using surface enhanced laser desorption/ionization-time of flight (SELDI-TOF) has been questioned. This investigation was designed to test the reproducibility of SELDI data collected over time by multiple users and instruments. Five laboratories prepared arrays once every week for six weeks. Spectra were collected on separate instruments in the individual laboratories. Additionally, all of the arrays produced each week were rescanned on a single instrument in one laboratory. Lab-to-lab and array-to-array variability in alignment parameters were larger than the variability attributable to running samples during different weeks. The coefficient of variance (CV) in spectrum intensity ranged from 25% at baseline, to 80% in the matrix noise region, to about 50% during the exponential drop from the maximum matrix noise. Before normalization, the median CV of the peak heights was 72% and reduced to about 20% after normalization. Additionally, for the spectra from a common instrument, the CV ranged from 5% at baseline, to 50% in the matrix noise region, to 20% during the drop from the maximum matrix noise. Normalization reduced the variability in peak heights to about 18%. With proper processing methods, SELDI instruments produce spectra containing large numbers of reproducibly located peaks, with consistent heights.

BISTABLE KINETIC MODEL DRIVEN BY AN INHOMOGENEOUS NOISE

Steady state properties of a Brownian particle moving in a bistable kinetic system is investigated in the presence of an inhomogeneous noise. It is found that the inhomogeneous noise makes the system change from two-state system to one-state system, namely, the inhomogeneous noise can induce a phase transition. The particle will always move from a large intensity noise region to a small intensity region.