Wyniki wyszukiwania - BazTech

1

Nowoczesne małowrażliwe materiały wybuchowe do celów wojskowych

Prasuła Piotr, Gołofit Tomasz, Kasprzak Piotr

Przemysł Chemiczny

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2023

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T. 102, nr 11

1162--1168

PL

Przegląd literatury pod kątem nowoczesnych kruszących materiałów wybuchowych charakteryzujących się obniżoną wrażliwością na bodźce zewnętrzne, w tym bodźce mechaniczne, takie jak uderzenie itarcie. Podano podstawowe właściwości poszczególnych materiałów wybuchowych wraz z parametrami detonacyjnymi, istotnymi z praktycznego punku widzenia. Możliwość wykorzystania danego materiału do celów wojskowych warunkowana jest również kosztami produkcji, co bezpośrednio wiąże się ze stopniem skomplikowania procesu syntezy oraz dostępnością niezbędnych odczynników chemicznych.

EN

A review, with 66 refs., of modern explosives, characterized by reduced sensitivity to external stimuli, including mech. ones, such as impact and friction. The basic properties of individual explosives responsible for reducing sensitivity to external stimuli and detonation parameters important from a practical point of view were given. These factors det. whether a given material or an explosive compn. based on it will find practical application.

2

The Numerical Analysis of the Elementary, Fractional Order, Interval Transfer Function

Oprzędkiewicz Krzysztof

Pomiary Automatyka Robotyka

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2023

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R. 27, nr 4

45--51

EN

In the paper the analysis of the impact of the interval uncertainty of parameters on the behaviour of the elementary Fractional Order (FO) transfer function is investigated. The fractional order and quasi time constant are defined as intervals describing deviation from nominal values. Such an analysis has not be considered yet. The proposed elementary, interval model can be applied in modeling of different, uncertain-parameters elements and physical phenomena. For the considered transfer function the methodology of its numerical analysis is proposed and illustrated by simulations. Results of numerical tests point that the best robustness of the model is achieved for relatively lower values of its parameters.

PL

W pracy zaprezentowano analizę wpływu przedziałowej niepewności parametrów na zachowanie się elementarnej transmitancji niecałkowitego rzędu. Parametry modelu: rząd ułamkowy i pseudo-stała czasowa są zdefiniowane jako przedziały opisujące odchyłki od wartości nominalnych. Tego typu analiza nie była do tej pory rozważana. Proponowany elementarny model przedziałowy może znaleźć zastosowanie do opisu różnych elementów i zjawisk fizycznych, dla których wartości parametrów są opisane jedynie w sposób przybliżony. Dla rozważanej transmitancji zaproponowano metodologię jego analizy numerycznej i zilustrowano ją symulacjami. Wyniki testów numerycznych wskazują, że model jest najbardziej odporny na niepewność parametrów dla ich relatywnie niskich wartości.

3

Optical simulations and optimization of highly sensitive biosensor for cancer cell detection

El Mouncharih Abdelkarim, Takassa Rabi, Farkad Omar, Tchenka Abdelaziz, Ibnouelghazi El Alami, Abouelaoualim Driss

Optica Applicata

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2023

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Vol. 53, nr 3

407--418

EN

In this work, using the two-dimensional finite difference time domain method, we are theoretically studying the optical properties of a two-dimensional photonic crystal biosensor based on silicon rods arranged as a square structure in an air bottom with two waveguides and a nanocavity. For this purpose, six different cells are infiltrated into the point defect. These six cells are Jurkat, HeLa, PC-12, MDA-MB-231, MCF-7, and basal cells. As a result, we have successfully detected cancer and benign cases of these cells through resonance peaks in the transmission spectrum. We evaluated the sensitivity, quality factor, detection limit, and figure of merit at different values for sensing region radius for optimization purposes. We report that we observed the maximum sensitivity of 1350 nm/RIU at 0.15 μm for the basal cell. Finally, the proposed biosensor can be a miniaturized structure with extreme sensitivity in cancer cell detection models.

4

An extrinsic Fabry–Pérot interference fiber sensor for ultrasonic detection of partial discharge

Zhang Ximin, Qian Sen, Liu Huixin, Chen Chuan, Deng Chuanlu, Hu Chengyong, Huang Yi

Optica Applicata

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2023

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Vol. 53, nr 2

199--211

EN

An ultrasonic sensor based on extrinsic Fabry–Pérot interference (EFPI) has been designed and demonstrated to detect the ultrasonic wave signal. The sensitivity and natural frequency of fiber Fabry–Pérot (F-P) sensor with different structure parameter have been simulated by COMSOL. The simulation results illustrate that the sensitivity is up to 1.737 nm/kPa and the natural frequency is 2.1 MHz, when the silica diaphragm thickness is 2 μm, the radius is 90 μm, and the cavity length is 18 μm. The most suitable parameters have been selected and the F-P sensor has been fabricated. When the ultrasonic signals with the frequencies of 40 kHz and 1.2 MHz are respectively applied to the sensor, the frequencies detected by the EFPI ultrasonic sensor are 39 kHz and 1.21 MHz based on a partial discharge detection experiment for the designed demodulation system. The experimental results show that the sensor can accurately detect ultrasonic signals. As an excellent platform for ultrasonic signal sensing, this EFPI ultrasonic sensing system has great potential applications in partial discharge detection field.

5

Dynamic tilt testing of MEMS inclinometers based on conical motions

Yang Qihang, Cai Chenguang, Yang Ming, Kong Ming, Liu Zhihua, Liang Feng

Metrology and Measurement Systems

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2023

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Vol. 30, nr 1

31--47

EN

The MEMS inclinometer integrates a tri-axis accelerometer and a tri-axis gyroscope to solve the perceived dynamic inclinations through a complex data fusion algorithm, which has been widely used in the fields of industrial, aerospace, and monitoring. In order to ensure the validity of the measurement results of MEMS inclinometers, it is necessary to determine their dynamic performance parameters. This study proposes a conical motion-based MEMS inclinometer dynamic testing method, and the motion includes the classical conical motion, the attitude conical motion, and the dual-frequency conical motion. Both the frequency response and drift angle of MEMS inclinometers can be determined. Experimental results show that the conical motions can accelerate the angle drift of MEMS inclinometers, which makes them suitable for dynamic testing of MEMS inclinometers. Additionally, the tilt sensitivity deviation of the MEMS inclinometer by the proposed method and the turntable-based method is less than 0.26 dB. We further provide the research for angle drift and provide discussion.

6

Device for measurement and control of humidity in crude oil and petroleum products

Semenov Andriy, Zviahin Oleksander, Kryvinska Natalia, Semenova Olena, Rudyk Andrii

Metrology and Measurement Systems

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2023

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Vol. 30, nr 1

195--208

EN

A device with a frequency-modulated output signal has been developed to increase the sensitivity and accuracy of measuring moisture content in crude oil and petroleum products in the range of 0~20%. The main element of the device is a self-oscillator transducer based on a transistor structure with negative differential resistance. A capacitive sensor in the form of a capacitive cylindrical structure with cylindrical electrodes was used to determine moisture content in crude oil and petroleum products. Electric permittivity of a two-component mixture of oil and water was estimated and the capacitance of the humidity-sensitive capacitive cylindrical structure with cylindrical electrodes was calculated. An electrical diagram of the device for measuring and controlling the humidity of crude oil and petroleum products has been developed. The relative error of converting the humidity of oil and petroleum products into capacitance which was caused by the change in oil temperature, was determined to be 0.225%. Values of relative errors of the device for measuring the humidity of oil and petroleum products are as follows: 1.355 · 10-5% is caused by instability of the oscillator frequency, 0.01% is caused by fluctuations in the supply voltage of the self-oscillator transducer, 0.05% is caused by a change in ambient temperature by 1°C. For the developed device, which used errors of the first and second type, the reliability of humidity control of oil and petroleum products has been determined to be 0.9591.

7

Evaluation of Modular J-PET sensitivity

Tayefi Ardebili Faranak, Niedźwiecki Szymon, Moskal Paweł

Bio-Algorithms and Med-Systems

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2023

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Vol. 19, no. 1

132--138

EN

The Modular J-PET represents the latest advancement in the Jagiellonian-PET series, utilizing extended plastic scintillator strips. This prototype's modular design enables cost-effective imaging of multi-photon annihilation and positronium, allowing for easy assembly, portability, and versatility. Additionally, its lightweight construction facilitates static bed examinations with a mobile detection system that can be positioned conveniently alongside the patient, negating the requirement for spacious clinical settings. Comprising 24 modules arranged in regular 24-sided polygons circumscribing a 73.9 cm diameter circle, each module integrates 13 scintillator strips, measuring 50 cm in length and 6 mm × 24 mm in cross-section. Scintillation light is captured at both ends through analog Silicon Photomultipliers (SiPMs). This research presents Sensitivity of the Modular J-PET tomograph, adhering to the NEMA_NU 2-2018 standards. Sensitivity measurement was performed with 68Ge line source inside the 5 sleeves aluminium phantom placed at center of the detector`s field-of-view (FOV) and 10 cm offset from the center of detector. Analyzing the gathered data involved employing the specialized J-PET Framework software, developed within the C++ architecture. To validate the experimental findings, comparisons were made with GATE simulations, wherein the source and phantom were emulated in the same configuration as employed in the actual experiment. The system sensitivity of the Modular J-PET was assessed to be 1.03 ± 0.02 cps/kBq in the center of the detector`s FOV with the peak sensitivity of 2.1 cps/kBq. However, the simulations indicate that at the center of the detector's FOV, the Modular J-PET achieves a system sensitivity of 1.32 ± 0.03 cps/kBq, with a peak sensitivity of 2.9 cps/kBq.

8

Implicit neural state functions in hybrid reliability analysis of plane frame

Potrzeszcz-Sut Beata, Dudzik Agnieszka, Radoń Urszula

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

55--71

EN

The objective of the article involves presenting innovative approach to the assessment of structural reliability analysis. The primary research method was the First Order Reliability Method (FORM). The Hasofer-Lind reliability index in conjunction with transformation method in the FORM was adopted as the reliability measure. The implicit limit state functions were used in the analysis. The formulation of the random variables functions were created in the Matlab software by means of neural networks (NNs). The reliability analysis was conducted in Comrel module of Strurel computing environment. In the proposed approach, Hybrid FORM method (HF) used the concept in which NNs replaced the polynomial limit state functions obtained from FEM (Finite Elements Method) for chosen limit parameters of structure work. The module Comrel referenced Matlab files containing limit state functions. In the reliability analysis of structure, uncertain and uncorrelated parameters, such us base wind speed, characteristic snow load, elasticity modulus for steel and yield point steel are represented by random variables. The criterion of structural failure was expressed by four limit state functions - two related to the ultimate limit state and two related to the serviceability limit state. Using module Comrel values of the reliability index with the FORM method were determined. Additionally, the sensitivity of the reliability index to random variables and graph of partial safety factors were described. Replacing the FEM program by NNs significantly reduces the time needed to solve the task. Moreover, it enables the parallel formulation of many limit functions without extending the computation time.

PL

Obecnie ocena niezawodności konstrukcji bazuje na wyidealizowanej koncepcji stanów granicznych i ich weryfikacji poprzez zastosowanie częściowych współczynników bezpieczeństwa. Rolą częściowych współczynników bezpieczeństwa jest zapewnienie wymaganego poziomu niezawodności konstrukcji. Metody probabilistyczne są naturalnym rozszerzeniem metody stanów granicznych. W praktycznych zastosowaniach istniejące oprogramowanie MES (Metoda Elementów Skończonych) jest często łączone z modułami do analizy niezawodności. Wadą takiego podejścia jest jednak długi czas obliczeń wynikający z wielokrotnych wywołań funkcji stanu granicznego dla różnych realizacji wektora zmiennych losowych. W artykule autorzy proponują alternatywne rozwiązanie problemu poprzez implementację hybrydowej metody FORM. Ocenę prawdopodobieństwa awarii, a tym samym obliczenie wskaźnika niezawodności Hasofera-Linda, uzyskujemy poprzez zastosowanie metody aproksymacyjnej FORM. W analizie wykorzystano niejawne funkcje stanów granicznych. Formułowanie funkcji granicznych dla pewnego zakresu zmiennych losowych zostało utworzone w programie Matlab za pomocą sieci neuronowych (SN). Analiza niezawodności została przeprowadzona w module Comrel środowiska obliczeniowego Strurel. Pakiet ten zawiera wbudowane interfejsy do definiowania funkcji stanów granicznych umożliwiając odwołanie do plików Matlaba zawierających zdefiniowane przez użytkownika funkcje stanu. Proponowana przez autorów hybrydowa metoda FORM łączy trzy algorytmy obliczeniowe - metodę elementów skończonych, sieci neuronowe oraz metodę aproksymacyjną probabilistycznej oceny niezawodności konstrukcji - FORM. Struktura algorytmu systemu jest więc mieszana, tzn. szeregowo-równoległa. Analiza zadania przebiega w czterech etapach.

9

Investigation of aquifer vulnerability and sensitivity analysis of modified drastic and sintacs models: a case study of Ovogovo Area, Eastern Nigeria

Omeje Emmanuel T., Obiora Daniel N., Okeke Francisca N., Ibuot Johnson C., Ugbor Desmond O., Omeje Victor D.

Acta Geophysica

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2023

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Vol. 71, no. 5

2439--2464

EN

Groundwater serves as a useful source of freshwater to man. Its protection and assessment of potential exposure to contamination are imperative, as its remediation when contaminated is extremely challenging. Vertical electrical sounding was carried out in twenty (21) locations of Ovogovo area with the aim to evaluate the vulnerability of groundwater to pollution, using four vulnerability indexed-based models. Results from DRASTIC AND SINTACS models delineated low and moderate vulnerable zones, while DRASTICLu and SINTACSLu, establishing an index range of 177 to 191 and 160 to 174, respectively, delineated eleven (11) locations as highly vulnerable to contamination. The four models characterized six locations as moderately vulnerable. Statistical summary of DRASTICLu and SINTACSLu models identified high risk of aquifer contamination to originate from recharge and soil media, with a very low risk of contamination, emanating from nature of vadose zone, aquifer nature, topography and land use. Results from single parameter sensitivity and map removal analysis for the modified models delineated depth to water table and land use as the most sensitive parameters in vulnerability assessment of Ovogovo area. Single or multiple map removal analysis identified an increment in sensitivity to vulnerability index as more parameters were being removed. The integration of these vulnerability models and sensitivity analysis enhanced good interpretation of the estimated vulnerable zones. These results will serve as a guide to governmental and non-governmental bodies in understanding the Ovogovo groundwater vulnerability characteristics and sensitization of habitants against indiscriminate disposal of waste and other harmful contaminants for preservation of its groundwater.

10

Sensitivity of Aerodynamic Characteristics of Paraglider Wing to Properties of Covering Material

Maślanka Paulina, Korycki Ryszard

Autex Research Journal

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2022

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Vol. 22, no. 1

64--72

EN

The paper is theoretically oriented. The main goal is to analyze the sensitivity of aerodynamic characteristics to the properties of the material used for paraglider wing. The paraglider of considerable dimensions is designed without stiffening elements. Thus, the covering material yields adequate pressure distribution between the external and internal parts of the wing. The problem is solved using a geometrical model approximated by the dimensionless coordinates of crucial points and smoothed by spline curves. The finite volume mesh is defined using the Ansys Meshing program. Numerical analysis uses five different covering materials, ranging from the air-impermeable covering to the covering subjected to hydrolytic-mechanical degradation. Optimization of properties of the covering material improves the lift force and the aerodynamic characteristics of the wing. Moreover, numerical modeling is more beneficial and efficient than prototype tests. The obtained pressure distributions and other parameters explain the aerodynamic safety of the paraglider during dynamic conditions of flight.

11

A review of the current state-of-the-art in Fano resonance-based plasmonic metal-insulator-metal waveguides for sensing applications

Adhikari R., Chauhan D., Mola G. T., Dwivedi R. P.

Opto-Electronics Review

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2021

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Vol. 29, No. 4

148--166

EN

Fano resonance is an optical effect that emerges from the coherent coupling and interference (constructive and destructive) between the continuous state (background process) and the Lorentzian state (resonant process) in the plasmonic waveguide-resonator system. This effect has been used in the applications like optical sensors. These sensors are extensively used in sensing biochemicals and gases by the measurement of refractive index changes as they offer high sensitivity and ultra-high figure of merit. Herein, we surveyed several plasmonic Fano sensors with different geometries composed of metal-insulator-metal waveguide(s). First, the resonators are categorized based on different architectures. The materials and methods adopted for these designs are precisely surveyed and presented. The performances are compared depending upon the characterization parameters like sensitivity and figure of merit. Finally, based on the survey of very recent models, the advances and challenges of refractive index sensing deployed on Fano resonances are discussed.

12

Investigations on the luminescence properties of quartz and feldspars extracted from loess in the Canterbury Plains, New Zealand South Island

Brezeanu D., Avram A., Micallef A., Cinta Pinzaru S., Timar-Gabor A.

Geochronometria

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2021

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Vol. 48, no.1

46--60

EN

The applicability of the single-aliquot regenerative-dose (SAR) protocol, by using the optically stimulated luminescence (OSL) signal of quartz as well as the post-infrared–infrared (pIRIR) signals of polymineral fine grains, namely pIRIR225 and pIRIR290, was assessed for dating loess in New Zealand South Island. OSL signals of quartz grains displayed low sensitivity. However, the application of repeated irradiation/bleaching cycles did not result in an increase in sensitivity; annealing in the 300–500°C temperature range generated the sensitisation of both the 110°C thermoluminescence (TL) peak as well as the OSL signal, likely by activation of yet unidentified luminescence centres. After heating, the quartz signal is comparable to that of ideal samples, but the annealing is precluding successful dating. On the other hand, feldspar infrared-stimulated signals displayed satisfactory properties, allowing estimation of ages ranging from 14 ± 1–29 ± 3 ka for the investigated deposit. It was shown that pIRIR225 and pIRIR290 methods have potential for dating loess in the South Island of New Zealand, based on the following observations: (i) Dose recovery tests were successful with recovered-to-given dose ratios with a <10% deviation from unity, (ii) constant residual values of about 4 Gy and about 10 Gy were obtained after exposures for 48 h in the case of pIRIR225 signals and 96 h in the case of pIRIR290 signals, respectively, (iii) while a slight dose-dependence of the residual was reported, and for a dose as large as 1600 Gy the residual values are ≅9 Gy and ≅19 Gy for pIRIR225 and pIRIR290 signals, respectively.

13

Progress and perspectives in total body PET systems instrumentation

Vandenberghe Stefaan

Bio-Algorithms and Med-Systems

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2021

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Vol. 17, no. 4

265--267

EN

Total body positron emission tomography (PET) systems are being developed by different groups worldwide. These systems have potential to change the number of applications in which molecular imaging is used. The change from a short axial field of view (FOV) to a longer one is however associated with a linear increase in the cost of these systems. This may limit their application to a small number of centers (capable of obtaining sufficient research funding). Therefore it remains interesting to see if lower cost systems can be developed and bring total body PET to the clinic for an acceptable budget. The wider availability of this low cost system can also enable more researchers to further optimize and explore the full potential of total body PET.

14

The sensitivity of the process of optimal decisions making in electrical networks with renewable energy sources

Lezhniuk Petro, Komar Vyacheslav, Rubanenko Olena, Ostra Natalia

Przegląd Elektrotechniczny

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2020

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R. 96, nr 10

32--38

EN

Are showed the necessity of the functioning of control automatization systems of conditions of bulk power system with renewable energy sources (RES) by taking into account the sensitivity. It is advisable to carry out optimal control of the bulk power system by introducing control parameters into the optimality (insensitivity) area. The permissible deviation range of the control parameters from their optimal values is determined by the solution of the direct and reverse sensitivity of the task. The direct and indirect tasks of the sensitivity can and should be solved in relative units using similarity theory methods. Showed that in this case the limits of the permissible optimality range are determined analytically. Comparing the allowable values of the optimality of the individual control parameters, it is possible to rank them and set the appropriate order and intensity of their actions. This makes it possible to compensate for the disturbances in the bulk power system that are carried out due to the instability of RES generation, in the most rational way.

PL

Wskazane jest przeprowadzenie optymalnej kontroli systemu zasilania jałowego poprzez wprowadzenie parametrów kontrolnych w obszarze optymalności (niewrażliwości). Dopuszczalny zakres odchyleń parametrów kontrolnych od ich wartości optymalnych jest określony przez rozwiązanie bezpośredniej i odwrotnej czułości zadania. Zadanie czułości bezpośredniej i odwrotnej można i powinno być rozwiązywane w jednostkach względnych przy użyciu metod teorii podobieństwa. Wykazanoź, że w tym przypadku granice dopuszczalnego zakresu optymalności są ustalane analitycznie. Porównując dopuszczalne wartości optymalności poszczególnych parametrów kontrolnych, można je uszeregować i ustawić odpowiednią kolejność i intensywność ich działań. Pozwala to w najbardziej racjonalny sposób zrekompensować zakłócenia w systemie zasilania, które są spowodowane niestabilnością wytwarzania odnawialnych źródeł energii.

15

Single air-mode resonance photonic crystal nanofiber cavity for ultra-high sensitivity refractive index sensing

Zhang Yanni, Yang Jiaxi, Song Meiqi, Zhang Xuan, Yang Daquan

Optica Applicata

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2020

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Vol. 50, nr 2

199--207

EN

We propose a design of series-connected one-dimensional photonic crystal nanofiber cavity sensor (1-D PC-NCS) and one-dimensional photonic crystal nanofiber bandgap filter (1-D PC-NBF). The proposed structure can get a single air mode for refractive index sensing with its extinction ratio of 58.64 dB. It filters out the high order mode and reduces the interaction between signals. By 3D FDTD, the calculated sensitivity is 848.18 nm/RIU (RIU – refractive index unit). Compared with general silicon on-chip nanobeam cavity, the sensitivity is increased by eight times. The additional 1-D PC-NBF will not change the sensitivity and the position of the resonance wavelength. Therefore, the new design we propose addresses the issue of crosstalk, and can be applied to ultra-high sensitivity index-based gas sensing and biosensing without the need for complicated coupling systems.

16

Effect of the Molecular Structure and Molecular Weight of Poly(Vinylidene Fluoride-Chlorotrifluoroethylene) Copolymers on the Characteristic Properties of TATB-based Composites

Singh Arjun, Sharma Tirupati Chander, Kumar Mahesh

Central European Journal of Energetic Materials

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2020

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Vol. 17, no. 3

428--450

EN

1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) based composites with different molecular weights and molecular structures of poly(vinylidene fluoride-chlorotrifluoroethylene) (poly(VDF-CTFE) binder were studied to investigate their effect on the physical, thermal, mechanical and explosive properties. The poly(VDF-CTFE) with three different kinds of molecular weights (FKM1, FKM2 and FKM3 samples) and three different kinds of molar ratios of VDF and CTFE (FKM4, FKM5and FKM6) was chosen as the polymeric binder. The experimental results indicated that all of these kinds of TATB-based composites do not show any measurable changes in the particle density, detonation velocity and impact sensitivity. The thermal data revealed that weight loss occurs in two steps and, that the thermal stability deceases slightly with an increase in the molecular weight. On other hand, the weight loss occurred in a single step and the thermal stability increases slightly with an increase in the molar ratio of the CTFE to VDF monomer units. The adhesion properties between the two phases of TATB crystals and polymeric matrices rely on the properties of the interface, which is expressed in terms of the mechanical properties. The storage modulus decreases with increasing molecular weight. On other hand, an increase in the CTFE to VDF molar ratio in the poly(VDF-CTFE) binder remarkably improves the mechanical strength. FKM5-9505 shows a significant reduction in creep deformation and dramatically increases the elongation failure, compared to those of the FKM4-9505 sample. Finally, SEM observations clearly suggested that the coating of the polymer matrix onto the surface of the TATB crystals is clearly demonstrated.

17

Data Mining-Based Phishing Detection

Bohacik Jan, Skula Ivan, Zabovsky Michal

Annals of Computer Science and Information Systems

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2020

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Vol. 21

27--30

EN

Webpages can be faked easily nowadays and as there are many internet users, it is not hard to find some becoming victims of them. Simultaneously, it is not uncommon these days that more and more activities such as banking and shopping are being moved to the internet, which may lead to huge financial losses. In this paper, a developed Chrome plugin for data mining-based detection of phishing webpages is described. The plugin is written in JavaScript and it uses a C4.5 decision tree model created on the basis of collected data with eight describing attributes. The usability of the model is validated with 10-fold cross-validation and the computation of sensitivity, specificity and overall accuracy. The achieved results of experiments are promising.

18

Efects of anisotropic changes on the conductivity of sedimentary aquifers, southeastern Niger Delta, Nigeria

George N. J., Bassey N. E., Ekanem A. M., Thomas J. E.

Acta Geophysica

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2020

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Vol. 68, no. 6

1833--1843

EN

Sundry soils/rocks are characterized by electrical properties with clearly or obscurely expressed anisotropies. These anisotropic efects may be low, moderate or high depending on the coefcient of anisotropy (λ). The vertical electrical sounding technique employing Schlumberger electrode confguration and lithological information from boreholes were deployed to characterize the lithological diversity in homogeneous and anisotropic geologic units that serve as aquifer systems and their overlaying layers in the coastal region of Akwa Ibom State. Based on the λ, the assessed volume of sedimentary formation is classifed into low anisotropy λ<1.2 , moderate anisotropy (1.2 < λ ≤ 1.3) and high anisotropy (λ > 1.3) with alluvium (64.3%), inter-bedded shale and sandstone (14.3%) and shale and slate (21.3%). The estimated percentage of respective compositional coverage indicates that alluvium is dominant, while the blended inter-bedded shale and sandstone as well as the shale and slate are minor geologic units in the Benin Formation. Inferred index of spread of alluvium indicates that the homogeneous and anisotropic units assessed are intrinsic/microscopic in nature as identifed by the impressed current that passed through geologic system. The results showcased that the plot between the strike-dependent resistivity ( ρθ ) at arbitrary chosen strike and geometric mean resistivity ( ρm ) can be used as a yardstick for inferring the degree of consistency of geologic compositions in homogeneous and anisotropic media. Both the quantitative (graphic) and qualitative (contour) results portend the thin possibility of having anisotropy free geologic units. The finding proposes that ground resistivity measurements and interpretations of geologic structures should be constrained by borehole information in order to frm up the intended plans for obtaining clearer, defendable and well-resolved subsurface structures.

19

Pomiar oraz porównanie wrażliwości różnych realizacji filtrów FIR 3D

Poczekajło Paweł

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

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2019

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Nr 14

77--82

PL

W artykule przedstawiono wyniki pomiaru wrażliwości charakterystyki amplitudowej na kwantowanie współczynników dla różnych realizacji filtrów cyfrowych. Przeanalizowano filtry separowalne FIR 3D w realizacji bezpośredniej (splot) i ortogonalnej z zastosowaniem rotatorów. Pomiar wrażliwości sprowadzono do wyznaczenia błędu średniokwadratowego charakterystyki amplitudowej. Wykorzystano trzy poziomy kwantowania współczynników (8-, 16- i 24-bity) oraz cztery rodzaje filtrów (dolnoprzepustowe, górnoprzepustowe, środkowoprzepustowe i środkowozaporowe).

EN

Measurements for sensitivity of amplitude characteristic on coefficients quantization for different realisation of digital filters is presented in the paper. Separable 3D filters in direct realisation (convolution) and orthogonal realisation with use rotation are analysed. Sensitivity is measured like a mean squared error of amplitude characteristic. Three quantization levels of coefficients (8-, 16- and 24bits) and four type of filters (low-pass, high-pass, band-pass and band-stop) are used.

20

GATE Simulation Study of the Siemens Biograph mCT 20 Excel PET/CT System

Saaidi Rahal, Toufique Yassine, Zeghari Abdelkrim, El kharrim Abderrahman, Cherkaoui El Moursli Rajaâ

Polish Journal of Medical Physics and Engineering

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2019

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Vol. 25, Iss. 1

7--14

EN

We used GATE simulation to study the effect of the coincidence time window (CTW) along with the block gap and the intercrystal gap on the count rate performance and the spatial resolution of the Biograph™ mCT 20 Excel. We ran simulations on our local cluster to reduce computation time. The task was split into several jobs that were then triggered simultaneously on the cluster nodes. The BiographTM mCT 20 Excel was validated using the NEMA NU 2-2012 protocol. Our results showed good agreement with experimental data. The simulated sensitivity, peak true count rate, peak noise equivalent count rate (NECR), and scatter fraction showed agreement within 3.62%, 5.77%, 0.6%, and 2.69%, respectively. In addition, the spatial resolution agreed within <0.51 mm. The results showed that a decrease in the coincidence time window and the block gap and an increase in the intercrystal gap increase the count rate performance and improve the spatial resolution. The results also showed that decreasing the coincidence time window increased the NECR by 27.37%. Changing the intercrystal gap from 0 to 0.2 mm and the block gap and from 4 to 0.4 mm increased the NECR by 5.53% and improved the spatial resolution at 1 cm by 2.91 % and that at 10 cm by 3.85%. The coincidence time window, crystal gap, and block gap are important parameters with respect to improving the spatial resolution.