ABOUT HEAD WAVES AND UNDER-SURFACE LONGITUDINAL WAVES, RADIATED BY THE NORMAL PROBE WHICH IS TAKING PLACE ON A FREE FLAT SURFACE OF THE ELASTIC ENVIRONMENT

On the basis of integrated representations Fourier–Bessel a component of displacement of elastic waves, radiating by the normal converter which is taking place on a free flat surface of the elastic environment, receives analytical estimations of displacement a under-surface longitudinal and head (it is surface-longitudinal) waves. Components of displacement a under-surface longitudinal wave are the sum a component in approximation of geometrical acoustics (GA), the diffraction amendments to this approximation and the amendments which are taking into account influence of feature when the parameter of integrated representation is equal to wave number of a longitudinal wave. Components of displacement of a head wave are defined as the sum appropriate diffraction amendments for a component of displacement of a volumetric longitudinal wave in approximation GA and a component of displacement of a lateral wave. The maximum of amplitude of displacement a under-surface longitudinal wave in angular area of a direction of distribution near to a free surface of environment is caused by one of local maxima of the directivity characteristic of the normal probe. Thus dependence of change of amplitude of this wave of distance wave from the centre of the probe practically corresponds to similar dependence for displacement of a volumetric longitudinal wave in GA approximation. Quantitative estimations of maxima of amplitude of displacement under-surface longitudinal and head waves concerning the greatest amplitude, radiated by the normal probe of a volumetric longitudinal wave.

INVESTIGATION OF THE POSSIBILITIES OF ULTRASONIC TESTING OF CAST IRON WITH LAMELLAR GRAPHITE USING STANDARD NORMAL PROBE

Computer simulation of acoustic paths for medium – cast iron with lamellar graphite for standard normal probe of several types was carried out in order to study the effect of such medium on the characteristics of transmitted and received signals during ultrasonic testing. In the course of studies to calculate the attenuation coefficient of longitudinal waves in cast iron with lamellar graphite, due to their Rayleigh and phase scattering by graphite inclusions, the previously developed model was used. Comparison of the results of calculations of spectra and pulses of the recorded signals for two samples of cast iron with lamellar graphite confirmed the possibility of using the developed calculation model for a description of real physical phenomena adequate for the practice of ultrasonic testing. The ratio of the recorded signal and structural noise levels for different models of transducers, reflectors and characteristics of the controlled cast iron is estimated. Shown that increased attenuation of the longitudinal wave in cast iron in comparison with steel as a result of scattering by inclusions leads to higher level of this noise and can greatly reduce the signal-to-noise ratio in the detection of the reflected from the defect signals.

Penerapan Metode Support Vector Machine pada Sistem Deteksi Intrusi secara Real-time

AbstrakSistem deteksi intrusi adalah sebuah sistem yang dapat mendeteksi serangan atau intrusi dalam sebuah jaringan atau sistem komputer, umum pendeteksian intrusi dilakukan dengan membandingkan pola lalu lintas jaringan dengan pola serangan yang diketahui atau mencari pola tidak normal dari lalu lintas jaringan. Pertumbuhan aktivitas internet meningkatkan jumlah paket data yang harus dianalisis untuk membangun pola serangan ataupun normal, situasi ini menyebabkan kemungkinan bahwa sistem tidak dapat mendeteksi serangan dengan teknik yang baru, sehingga dibutuhkan sebuah sistem yang dapat membangun pola atau model secara otomatis.Penelitian ini memiliki tujuan untuk membangun sistem deteksi intrusi dengan kemampuan membuat sebuah model secara otomatis dan dapat mendeteksi intrusi dalam lingkungan real-time, dengan menggunakan metode support vector machine sebagai salah satu metode data mining untuk mengklasifikasikan audit data lalu lintas jaringan dalam 3 kelas, yaitu: normal, probe, dan DoS. Data audit dibuat dari preprocessing rekaman paket data jaringan yang dihasilkan oleh Tshark.Berdasar hasil pengujian, sistem dapat membantu sistem administrator untuk membangun model atau pola secara otomatis dengan tingkat akurasi dan deteksi serangan yang tinggi serta tingkat false positive yang rendah. Sistem juga dapat berjalan pada lingkungan real-time. Kata kunci— deteksi intrusi, klasifikasi, preprocessing, support vector machine AbstractIntrusion detection system is a system for detecting attacks or intrusions in a network or computer system, generally intrusion detection is done with comparing network traffic pattern with known attack pattern or with finding unnormal pattern of network traffic. The raise of internet activity has increase the number of packet data that must be analyzed for build the attack or normal pattern, this situation led to the possibility that the system can not detect the intrusion with a new technique, so it needs a system that can automaticaly build a pattern or model.This research have a goal to build an intrusion detection system with ability to create a model automaticaly and can detect the intrusion in real-time environment with using support vector machine method as a one of data mining method for classifying network traffic audit data in 3 classes, namely: normal, probe, and DoS. Audit data was established from preprocessing of network packet capture files that obtained from Tshark. Based on the test result, the system can help system administrator to build a model or pattern automaticaly with high accuracy, high attack detection rate, and low false positive rate. The system also can run in real-time environment. Keywords— intrusion detection, classification, preprocessing, support vector machine

Concordance of a point mutation 5' to the A gamma-globin gene with A gamma beta + hereditary persistence of fetal hemoglobin in Greeks

In the Greek A gamma beta + type of hereditary persistence of fetal hemoglobin (HPFH), adult heterozygotes produce about 20% fetal hemoglobin (HbF), which is predominantly of the A gamma chain variety. The affected beta-globin gene cluster produces near normal amounts of beta-like globin, but in a A gamma to beta ratio of 20:80 instead of 0.5:99.5. Gelinas et al and Collins et al have shown a G to A change 117 nucleotides 5′ to the A gamma gene in two Greeks with A gamma beta + HPFH. To demonstrate that this change is not a neutral polymorphism, we carried out hybridization with oligonucleotide probes (19mers) specific for the normal and the mutant sequences. While normal probe identified the A gamma fragment in genomic DNA of all subjects studied, mutant probe was positive only in Greeks with A gamma beta + HPFH. In sum, 108 beta-globin gene clusters of individuals without HPFH were negative when tested with mutant probe, but all 11 affected individuals of six families with Greek A gamma beta + HPFH (two previously sequenced and four new families) were positive with mutant probe. These data support the conclusion that the -117 mutation is causative of A gamma beta + HPFH in Greeks.