Papers by Keyword: SNR

Abstract: UD. Pak Suandi is one of the UDs that produces and sells bricks. Many factors influence the quality of bricks, namely human resources, composition, and processing of raw materials. Brick making sometimes does not match the desired quality, there are often defects/cracks in the bricks. The method used in this research is the Taguchi method, where Taguchi is used to design efficient and effective experiments in identifying factors that influence brick quality, such as brick compressive strength, as well as to determine optimal settings of production parameters with the aim of maximizing brick quality. The results of this research show that the factors that have a significant influence are factors A (Clay) and D (Laban Tree Ash). The high SNR ANOVA value shows this. The optimal concentration settings are 1.40 kg of Clay, 45 ml of Water, 13 grams of Palm Ash and 14 grams of Laban Tree Ash. Where with the composition design, a compressive strength value of 9.73 MPa is obtained. The compressive strength obtained increased by 6.03 Mpa from the company's standard composition of 3.70 Mpa.

Abstract: Abstract. Magnetic Resonance Imaging (MRI) is a medical tool that is used to form images of organs, soft tissues, bones and almost all internal body structures. The MRI image acquisition process takes a long time. One of the efforts to shorten the examination acquisition time is using the parallel imaging technique, namely SENSE. However, SENSE has a weakness, namely reducing the Signal Noise to Ratio (SNR). One of the denoising methods that can increase SNR is the Nonlocal mean filter (NLM). Post-image acquisition denoising becomes a cheaper and more effective alternative to use. The aim of this research is to measure the increase of SNR value in MRI SENSE images between before the denoising technique and after the denoising technique. This research is expected to produce a faster scanning time and maintain the quality of the MRI image. This experimental research was carried out by applying the SENSE parallel imaging technique to R-factors 2 and 4. The sequence used is T2WI TSE on axial slice phantom. The T2WI TSE SENSE phantom MRI image was corrected with the NLM denoising technique to produce a better quality image. Each variation is measured image information before and after the denoising technique. Image information is assessed quantitatively by measuring SNR. The results of the parametric test showed that there was an increase in the SNR value after the application of the denoising technique on the Phantom T2WI TSE SENSE MRI image at r-factor 2 and r-factor 4. The different test on the SNR assessment resulted in a p value < 0.001.

Abstract: CBCT is a modernized technology in producing radiograph image on dentistry. The image quality excellence is very important for clinicians to interpret the image, so the result of diagnosis produced becoming more accurate, appropriate, thus minimizing the working time. This research was aimed to assess the image quality using the blank acrylic phantom polymethylmethacrylate (PMMA) (C­₅H₈O₂)_n in the density of 1.185 g/cm³ for evaluating the homogeneity and uniformity of the image produced. Acrylic phantom was supported with a tripod and laid down on the chin rest of the CBCT device, then the phantom was fixed, and the edge of the phantom was touched by the bite block. Furthermore, the exposure of the X-ray was executed toward the acrylic phantom with various kVp and mAs, from 80 until 90, with the range of 5 kV and the variation of mA was 3, 5, and 7 mA respectively. The time exposure was kept constant for 25 seconds. The samples were taken from CBCT acrylic images, then as much as 5 ROIs (Region of Interest) was chosen to be analyzed. The ROIs determination was analyzed by using the ImageJ® software for recognizing the influence of kVp and mAs towards the image uniformity, noise and SNR. The lowest kVp and mAs had the result of uniformity value, homogeneity and signal to noise ratio of 11.22; 40.35; and 5.96 respectively. Meanwhile, the highest kVp and mAs had uniformity value, homogeneity and signal to noise ratio of 16.96; 26.20; and 5.95 respectively. There were significant differences between the image uniformity and homogeneity on the lowest kVp and mAs compared to the highest kVp and mAs, as analyzed with the ANOVA statistics analysis continued with the t-student post-hoc test with α = 0.05. However, there was no significant difference in SNR as analyzed with the ANOVA statistic analysis. The usage of the higher kVp and mAs caused the improvement of the image homogeneity and uniformity compared to the lower kVp and mAs.

Abstract: Electrocorticography (ECoG) is receiving growing attention for both clinical and research applications thanks to its reduced invasiveness and ability of addressing large cortical areas. These benefits come with a main drawback, i.e. a limited frequency bandwidth. However, recent studies have shown that spiking activity from cortical neurons can be recorded when the ECoG grids present the following combined properties: (I) conformable substrate, (II) small neuron-sized electrodes with (III) low-impedance interfaces. We introduce here an ad-hoc designed ECoG device for investigating how electrode size, interface material composition and electrochemical properties affect the capability to record evoked and spontaneous neural signals from the rat somatosensory cortex and influence the ability to record high frequency neural signal components.Contact diameter reduction down to 8 μm was possible thanks to a specific coating of a (3,4-ethylenedioxytiophene)-poly (styrenesulfonate)-poly-(ethyleneglycol) (PEDOT-PSS-PEG) composite that drastically reduces impedance and increases electrical and ionic conductivities. In addition, the extreme thinness of the polyimide substrate (6 - 8 μm) and the presence of multiple perforations through the device ensure an effective contact with the brain surface and the free flow of cerebrospinal fluid. In-vivo validation was performed on rat somatosensory cortex.

Abstract: Dry sliding wear behaviours of polyamides of were investigated by Taguchi method using a pin-on-flat plate configuration. L9 orthogonal array and analysis of variance (ANOVA) were applied to investigate the influence of process parameters on wear rate. The experimental results indicated that Signal-to-Noise ratio (SNR) decreased with increasing elongation and decreased with increasing load slightly, but increased with increasing speed. ANOVA revealed that elongation at break exerted a great effect on the wear rate, which was followed by speed, respectively. Optimal process parameter was obtained for LFX type of polymer against smooth hardened steel.

Abstract: The high altitude meteorological data is the basic parameters for weapon system trajectory calculation, firing ballistic correction, and ballistic standardization. Measurement range weapon testing is essential to evaluate the final results, so it is accurate or not will directly influence the test. This paper outlines the wind profiler radar in guided missile range experiment and the necessity of working mechanism, and gives the testing environment of radar range test application and erection of wind profiles and parameter setting, finally derived horizontal wind speed measurement precision, theoretical radial velocity measurement accuracy, as well as the theoretical horizontal wind. Making the range test of wind profiler radar measured data can fit the fast and the theoretical solution of data, in order to test application range stroke profile radar has a more comprehensive understanding, and application of more mature and rational.

Abstract: Near field communication of HF radio is in the form of surface wave propagation. The propagation loss increases with the increase distance, but there is a certain regular. In addition to this, the communication quality relates to the background noise. In order to find the relationship between them, we obtain the relationship between effective communication distance and background noise through theoretical derivation in the 2FSK system. Simulation results show that the effective communication distance is shorter with the increase of carrier frequency and the decline of the ground conductivity. And the simulation results can play a guiding role for the estimation of the HF radio’s effective communication distance.

Abstract: Nowadays, RFID technology has been widely spread in various fields. However, the situation of the reader-to-reader collision, caused by movements of readers, is becoming more and more prominent. To solve this problem, this paper proposes an adaptive power control algorithm based on the SNR-measurements method, which uses the Kalman filtering algorithm to estimate the wireless channel characteristic at first, and then adjusts the transmission power of the reader variously according to both channel estimated results and SNR histories, which determines the step size. As shown in simulation results, the algorithm proposed could avoid reader-collision effectively. The algorithm not only provides improvements on real-time ability as well as reliability, but also improves the throughput and precision of identifying tags.

Abstract: High speed encoder is the key element of high speed analog-to-digital converter (ADC). Therefor the type of encoder, the type of code, bubble error suppression and bit synchronization must be taken into careful consideration especially for folding and interpolating ADC. To reduce the bubble error which may resulted from the circuit niose, comparator metastability and other interference, the output of quantizer is first encoded with gray code and then converted to binary code. This high speed encoder is verified in the whole time-interleaved ADC with 0.18 Bi-CMOS technology, the whole ADC can achieve a SNR of 45 dB at the sampling rate of 5GHz and input frequency of 495MHz, meanwhile a bit error rate (BER) of less than 10^-16 is ensured by this design.

Abstract: When we use the laser auto collimation theodolite to measure the azimuth error angle of air target, the strong noise background reduces the spot imaging quality and seriously influences the measuring angle ability of the theodolite. In order to solve the problem, a photoelectric detection system used to detect the weak signal is designed based the correlation detection principle and the principle of correlation detection technology is introduced. We use Simulink software presenting a simulation to the detection system and do a feasibility analysis. Finally, it’s proved that the photoelectric detection system could suppress the strong noise background, improve the SNR greatly and detect the weak signal effectively.