Wyniki wyszukiwania

Filtruj wyniki

  • Czasopisma
  • Autorzy
  • Słowa kluczowe
  • Data
  • Typ

Wyniki wyszukiwania

Wyników: 4
Wyników na stronie: 25 50 75
Sortuj wg:

Abstrakt

An emerging ultrasonic technology aims to control high-pressure industrial processes that use liquids at pressures up to 800 MPa. To control these processes it is necessary to know precisely physicochemical properties of the processed liquid (e.g., Camelina sativa oil) in the high-pressure range. In recent years, Camelina sativa oil gained a significant interest in food and biofuel industries. Unfortunately, only a very few data characterizing the high-pressure behavior of Camelina sativa oil is available. The aim of this paper is to investigate high pressure physicochemical properties of liquids on the example of Camelina sativa oil, using efficient ultrasonic techniques, i.e., speed of sound measurements supported by parallel measurements of density. It is worth noting that conventional low-pressure methods of measuring physicochemical properties of liquids fail at high pressures. The time of flight (TOF) between the two selected ultrasonic impulses was evaluated with a cross-correlation method. TOF measurements enabled for determination of the speed of sound with very high precision (of the order of picoseconds). Ultrasonic velocity and density measurements were performed for pressures 0.1–660 MPa, and temperatures 3–30XC. Isotherms of acoustic impedance Za, surface tension σ and thermal conductivity k were subsequently evaluated. These physicochemical parameters of Camelina sativa oil are mainly influenced by changes in the pressure p, i.e., they increase about two times when the pressure increases from atmospheric pressure (0.1 MPa) to 660 MPa at 30XC. The results obtained in this study are novel and can be applied in food, and chemical industries.

Przejdź do artykułu

Autorzy i Afiliacje

Piotr Kiełczyński
Stanisław Ptasznik
Marek Szalewski
Andrzej Balcerzak
Krzysztof Wieja
Aleksander J. Rostocki

Abstrakt

We report on the absorption properties of polarization-insensitive transmissive and reflective metamaterial absorbers based on two planar aluminium periodic structures and SU-8 epoxy resist. These absorbers were investigated using numerical simulation and experimental methods in the terahertz range (below 2 THz). SU-8 is a very promising organic material for dielectric layers in planar metamaterials, because its application simplifies the process of fabricating these structures and significantly reduces the fabrication time. The experimental absorption of the metamaterial absorbers has narrowband characteristics that were consistent with the numerical simulations. Power flow analysis in the transmissive metamaterial unit cell shows that the absorption in the terahertz range occurs primarily in the SU-8 layer of the absorber.

Przejdź do artykułu

Autorzy i Afiliacje

B. Grześkiewicz
A. Sierakowski
J. Marczewski
N. Pałka
E. Wolarz

Abstrakt

This paper expands the M-K curve theory with examples of the most commonly mentioned pile-soil mechanics behaviours in the literature and their corresponding κ2 variations. A brief introduction shows the history of the Meyer-Kowalow theory and its basic assumptions. This is followed by the relationship between in situ investigation CPT results, with parameters C1, C2, Ct used to approximate the load-settlement curve according to the M-K theory. The Meyer-Kowalow curve satisfies asymptotic behaviour for small loads, where linear theory applies, and for limit loads, when pile displacement is out of control. Essential in the description are constant parameters C, which refer to the aggregated Winklers modulus, Ngr limit loads and k, which is crucial for static load test results. For this reason, the authors sought to calculate the κ value based upon soil mechanics principles. This article shows methods for checking statistical mathematical calculations, published earlier by Meyer using CPT investigations. It presents real case calculations and directions for future planned research.

Przejdź do artykułu

Autorzy i Afiliacje

P. Siemaszko
Z. Meyer

Abstrakt

Przeprowadzone w formie analiz badania ustaleń miejscowych planów zagospodarowania przestrzennego i w części przypadków realizacji tych zapisów prawa miejscowego w praktyce wykazały, że ustalenia przestrzennego prawa miejscowego nie mają nic albo nie wiele wspólnego z zasadami kompozycji urbanistycznej i tym samym z ładem przestrzennym. Badania ograniczyły się do analizy komponowania zabudowy, bez uwzględnienia wszystkich innych uwarunkowań, jakie muszą towarzyszyć procesowi projektowania urbanistycznego i jego wyników. Urbanistykę w tym artykule traktuje się jako uporządkowaną przestrzeń, powstałą na podstawie czytelnej koncepcji urbanistycznej, która uwzględnia zasady kompozycji urbanistycznej. Nie odnosi się pojęcie urbanistyki do chaosu przestrzennego, jaki jest lub powstaje po realizacji ustaleń planu.

Przejdź do artykułu

Autorzy i Afiliacje

Elżbieta Czekiel-Świtalska

Ta strona wykorzystuje pliki 'cookies'. Więcej informacji