Performance analysis of non-reflective boundary conditions on sound localization problem in an isotropic plate.

Acoustic source localization, considering the effect of reflected waves from geometrical features (such as holes, lugs and structural discontinuities) is still one of the most challenging areas in this field. In this paper, the effects of reflected waves from edges on source localization results are discussed. Most of the previous studies have ignored the reflected waves by selection of the test zone far from the test plate edges. The current approaches for considering reflected waves are based on using high Sampling Rate Data (SRD) which is unsuitable for practical applications. This paper discusses how silicon dampers on edges affect the acoustic source localization on an isotropic plate using low SRD. In this approach, four silicon dampers are installed on a Plexiglas plate. The effect of each damper is experimentally tested on final prediction error. The experimental results reveal that the reduction of prediction error according to each damper highly depends on the impact and sensor location related to the damper's position.

A Molecular and Serological Study on Visceral Leishmaniasis in Asymptomatic Stray Dogs in Mashhad, Iran.

Zoonotic visceral leishmaniasis is caused by Leishmania infantum (L. infantum),and its major reservoir hosts are domestic dogs, most of which are asymptomatic. This study aimed to detect L. infantum spp. in asymptomatic stray dogs by molecular and serological methods in Mashhad, Iran, during 2011-12. In this study, 94 asymptomatic stray dogs were randomly selected and their blood samples were collected for indirect fluorescent antibody testing. Furthermore, tissue samples from all the L. infantum seropositive stray dogs were examined using semi-nested polymerase chain reaction (PCR). Accordding to the results, 11.7 %(11/94) of the dogs were L. infantum seropositive. The PCR positivity rate of L. infantum was 63.6% (7/11) in at least one of the collected specimens of the seropositive dogs. The L. infantum kinetoplast DNA (kDNA) was detected in the liver of 36% (4/11), the spleen of 27% (3/11), and the skin of 54.5 %(6/11) of the stray dogs. In this study, based on the molecular and serological examinations, visceral leishmaniasis infection among the stray dogs in Mashhad was confirmed.

Sound localization in an anisotropic plate using electret microphones.

Acoustic source localization without knowing the velocity profile in anisotropic plates is still one of the most challenging areas in this field. The current time-of-flight based approaches for localization in anisotropic media, are based on using six high sampling sensors. The number of sensors and the corresponding large amount of data, would make those methods inefficient in practical applications. Although there are many different non-time-of-flight based approaches such as machine learning, or soft computing based methods that can be used for localization with a less number of sensors, they are not as accurate as time-of-flight based techniques. In this article, a new approach which requires only four low sampling rate sensors to localize acoustic source in an anisotropic plate is proposed. In this technique, four electret low sampling rate sensors in two clusters are installed on the plate surface. The presented method uses attenuation analysis in a suitable frequency band to decrease the number of sensors. The approach is experimentally tested and verified on an airplane composite nose by applying artificially generated acoustic emissions (Hsu-Nielsen source). The results reveal that the accuracy of proposed technique depends on distinction of dominant frequency band. A stethoscope as a physical filter is employed to reduce the sensitivity of the technique and delineation of frequency band. The suggested technique improves the accuracy of localization prediction.

Locating the acoustic source in thin glass plate using low sampling rate data.

Acoustic source localization is an important step for structural health monitoring (SHM). There are many research studies dealing with localization based on high sampling rate data. In this paper, for the first time, acoustic source is localized on an isotropic plate using low sampling rate data. Previous studies have mainly used a cluster of specific sensors to easily record high sampling rate signals containing qualitative time domain features. This paper proposes a novel technique to localize the acoustic source on isotropic plates by simply implementing a combination of two simple electret microphones and Loci of k-Tuple Distances (LkTD) from the two sensors with low sampling rate data. In fact the method proposes substitution of previous methods based on solving the system of equations and increasing the number of sensors by implementing the selection of LkTD. Unlike most previous studies, estimation of time difference of arrival (TDOA) is based on the frequency properties of the signal rather than it's time properties. An experimental set-up is prepared and experiments are conducted to validate the proposed technique by prediction of the acoustic source location. The experimental results show that TDOA estimations based on low sampling rate data can produce more accurate predictions in comparison with previous studies. It is also shown that the selection of LkTD on the plate has noticeable effects on the performance of this technique.

QRS complex detection based on simple robust 2-D pictorial-geometrical feature.

In this paper a heuristic method aimed for detecting of QRS complexes without any pre-process was developed. All the methods developed in previous studies were used pre-process, the most novelty of this study was suggesting a simple method which did not need any pre-process. Toward this objective, a new simple 2-D geometrical feature space was extracted from the original electrocardiogram (ECG) signal. In this method, a sliding window was moved sample-by-sample on the pre-processed ECG signal. During each forward slide of the analysis window an artificial image was generated from the excerpted segment allocated in the window. Then, a geometrical feature extraction technique based on curve-length and angle of highest point was applied to each image for establishment of an appropriate feature space. Afterwards the K-Nearest Neighbors (KNN), Artificial Neural Network (ANN) and Adaptive Network Fuzzy Inference Systems (ANFIS) were designed and implemented to the ECG signal. The proposed methods were applied to DAY general hospital high resolution holter data. For detection of QRS complex the average values of sensitivity Se = 99.93% and positive predictivity P+ = 99.92% were obtained.

A serological study of Leishmania infantum in dogs of Khorasan Razavi province, Iran.

Leishmania infantum is the principal agent of visceral leishmaniosis (kala-azar) in all areas of Iran. The disease is endemic in Fars, Ardabil, East Azerbaijan and Bushehr provinces while it is sporadic in other parts of the country. Dog as a member of canidae family is the main animal reservoir host of kala-azar. The present study was carried out to determine the sero-prevalence of canine leishmaniosis in Mashhad, the capital city of Khorasan Razavi Province, in the north east of Iran. Two-hundred and nine dogs in two different classes including stray and sheepdogs were selected for this cross-sectional study. The blood samples were collected and tested by indirect immunofluorescent antibody test for detection of anti-Leishmania infantum antibodies. The results showed that 16/209 (7.6 %) of blood samples were positive. The sero-prevalence rates in stray and sheepdogs were 11/94 (11.7 %) and 5/115 (4.3 %), respectively (p < 0.05). Based on the results obtained, it is concluded that visceral leishmaniosis is distributed among dogs of this area, also sero-prevalence of canine leishmaniosis in stray dogs higher than sheepdogs.