Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 10
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

Gravity dewatering of fibrous suspension is one of basic technological operations in paper production process. Although there are numerous methods to determine dewatering of such suspensions, none of them can measure undisturbed flow of removed water. In the paper the idea and design of a new apparatus for the determination of drainage rate of fibrous suspensions is presented. The apparatus differs from other known devices by minimisation of filtrate flow resistance in the outlet part of the equipment. In the second part of the paper measurements of the drainage rate have been presented. The flow resistance of the fluid through the bottom wire screen in the device was determined. The calculated flow resistance will be used in the developed model of dynamic drainage of fibrous suspensions, which will be discussed in our following paper (Przybysz et al., 2014).

Go to article

Authors and Affiliations

Piotr Przybysz
Czesław Kuncewicz
František Rieger
Download PDF Download RIS Download Bibtex

Abstract

The long-ranging Early to Middle Triassic coniform conodont form-genus Cornudina Hirschmann occurs

abundantly in the Anisian of NW Turkey, Northern Tethys. Although suggested to represent the P1 element

of an apparatus of the Order Ozarkodinida Dzik, questions concerning the apparatus of Cornudina remain.

A description of the probable phylogenetic trends in the P1 elements of Cornudina is attempted and the role

of the form-genera Ketinella Gedik and Kamuellerella Gedik, as the alternative ramiform skeletal elements in

the Cornudina multi-element apparatus, is investigated. The newly described, Gedikella quadrata gen. nov.,

sp. nov., is an S element, Kamuellerella rectangularis sp. nov., is either an S3 or an S4 element, and Ketinella

goermueshi sp. nov., is an M element.

Go to article

Authors and Affiliations

Ali Murat Kılıç
Pablo Plasencia
Fuat Önder
Download PDF Download RIS Download Bibtex

Abstract

As part of the work the high-pressure sorptomat - a novel apparatus for sorption tests under conditions of high gas pressure was developed. The sorption measurement is carried out using the volumetric method, and the precise gas flow pressure regulator is used in the device to ensure isobaric conditions and regulate the sorption pressure in the range of 0-10 MPa. The uniqueness and high precision of sorption measurements with the constructed apparatus are ensured by the parallel use of many pressure sensors with a wide measurement range as well as high precision of measurement - due to the use of precise pressure sensors. The obtained results showed, i.a. that the time of reaching the isobaric conditions of the measurement is about 6-7 seconds and it is so short that it can be considered a quasi-step initiation of sorption processes. Moreover, the results of the measurement pressure stabilization tests, during the CO 2 sorption test on activated carbon, have shown that the built-in pressure regulator works correctly and ensures isobaric sorption measurement conditions with the precision of pressure stabilization of ±1% of the measurement pressure. The maximum range of sorption measurement using the high-pressure sorptomat is 0-86400 cm 3/g, and the maximum measurement uncertainty is ±2% of the measured value. The activated carbon sample used for the tests was characterized by a high sorption capacity, reaching 104.4 cm 3/g at a CO 2 pressure of 1.0 MPa.
Go to article

Authors and Affiliations

Mateusz Kudasik
1
Łukasz Anioł
1
Norbert Skoczylas
1
ORCID: ORCID

  1. Strata Mechanics Research Institute of the Polish Academy of Sciences, ul. Reymonta 27, 30-059 Cracow, Poland
Download PDF Download RIS Download Bibtex

Abstract

A simple analytical method for determination of basic hydrodynamic characteristics of hybrid fluidized-bed air-lift devices was presented. These devices consist of two parts: a two-phase air-lift part and a two-phase liquid-solid fluidized-bed part. Forced circulation of fluid in the air-lift part is used for fluidization of solid particles in the fluidized-bed part. According to the opinion given in the literature, if such apparatus is used for aerobic microbiological processes, its advantage is lower shear forces acting on the biofilm immobilized on fine-grained material compared with shear forces in three-phase fluidized-bed bioreactors. Another advantage is higher biomass concentration due to its immobilization on fine particles, compared with two-phase airlift bioreactors. A method of calculating gas hold-up in the air-lift part, and gas and liquid velocities in all zones of the analyzed apparatus is presented.

Go to article

Authors and Affiliations

Bolesław Tabiś
Dominika Boroń
Download PDF Download RIS Download Bibtex

Abstract

The paper reports a comparative study of the female gametophyte and especially synergid structure in sexual and apomictic dandelions. We analyzed diploid sexually reproducing Taraxacum linearisquameum (2n = 2x = 16) and two triploids, T. alatum and T. udum (2n = 3x =24), with autonomous embryo and endosperm development. There were no observed differences in the organization of the mature megagametophyte between the examined species. Both meiotically reduced and diplosporous embryo sacs showed typical polarity of the egg apparatus cells, together with development of a filiform apparatus in the synergids, but immunocytochemical analyses indicated that microtubules form longitudinal brush-like bundles adjacent to the filiform apparatus in the synergids of the sexual T. linearisquameum. This arrangement of cytoskeletal elements is similar to the configuration described in other amphimictic plants. The synergids of the apomictic T. alatum and T. udum show a uncharacteristic and relatively weak cytoskeleton with no brush-like bundles. We discuss the role of synergids in autonomous apomicts.

Go to article

Authors and Affiliations

Krystyna Musiał
Maria Kościńska-Pająk
Download PDF Download RIS Download Bibtex

Abstract

On the basis of induction heating, radiation heating and liquid nitrogen refrigeration, high-temperature, medium-temperature, normal-temperature and low-temperature heating/refrigeration furnaces were designed, respectively. An apparatus with a wide temperature range and high accuracy applied to test oxidation resistance of materials has been developed based on the thermogravimetric method and the heat transfer principle. The apparatus consists of four heating/cooling systems, a specimen fixture positioning unit, a laser positioning unit, vertical and horizontal moving guide rails, and a high-precision weighing balance. The apparatus, based on the thermogravimetric method, is able to test oxidation resistance of materials. In the test, the temperature range was −180∼3000◦C (the highest temperature is determined by material properties). The temperature control accuracy was ±5◦C. The accuracy of on-line weighing was ±0:1 mg. The measurement uncertainty was 0.2 mg. Compared with other relevant devices, this apparatus has its own advantages: simple operation, wide heating/cooling temperature range, sufficient specimen heating, high sensitivity and precision, and short heating/cooling time. The experimental results show that the developed apparatus presented in this study not only can be used for isothermal thermogravimetric tests, but also for thermal cycling tests and multi-step oxidation tests. With the effective integration of multiple heating apparatus and refrigeration apparatus, the apparatus breaks through the limitations of the heating/cooling temperature range of the existing devices, accomplishes the high-precision oxidation resistance test of materials in a wide temperature range, and will play a great role in improving the research of materials.

Go to article

Authors and Affiliations

Dong-Yang An
Jing-Min Dai
Peng Xiao
Download PDF Download RIS Download Bibtex

Abstract

In this study, the synthesis of lithium carbonate (Li2CO3) powder was conducted by a carbonation process using carbon dioxide gas (CO2) from waste acidic sludge based on sulfuric acid (H2SO4) containing around 2 wt.% lithium content. Lithium sulfate (Li2SO4) powder as a raw material was reacted with CO2 gas using a thermogravimetric apparatus to measure carbonation conditions such as temperature, time and CO2 content. It was noted that carbonation occurred at a temperature range of 800℃ to 900℃ within 2 hours. To prevent further oxidation during carbonation, calcium sulfate (CaO4S) was first introduced to mixing gases with CO2 and Ar and then led to meet in the chamber. The lithium carbonate obtained was examined by inductively coupled plasma–mass spectroscopy (ICP-MS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and it was found that of lithium carbonate with a purity above 99% was recovered.

Go to article

Authors and Affiliations

Dong Hyeon Choi
Jei Pil Wang
Download PDF Download RIS Download Bibtex

Abstract

The features of respiratory noises and noises of fins for open-circuit scuba divers, indicating a multipole character of noises emission, are specified in cameral conditions. It demonstrates a possibility to detect low-frequency components of noises of fins with pressure gradient sensor in near field. A possibility of estimating the respiratory rate of an open-circuit scuba diver is demonstrated at distances up to 100 m in real sea. It gives an opportunity of estimating the bearing (time delay in a pair of hydrophones) for the open-circuit scuba diver by respiratory noises at distances up to 150 m in real sea. Thus, low-frequency underwater noises of open-circuit scuba divers may be successfully applied to monitor the safety of diving and to prevent waterside intrusion by trespassers.

Go to article

Authors and Affiliations

Vladimir Korenbaum
Anatoly Kostiv
Sergey Gorovoy
Veniamin Dorozhko
Anton Shiryaev
Download PDF Download RIS Download Bibtex

Abstract

The aim of the study was to determine the influence of the load on the water accumulation embankment crown on changes in the course of the filtration curve in its body. The study was carried out with a medium-size filtration apparatus. We made a model of hydrotechnical embankment with the following dimensions. Width: base 2.0 m, crown 0.5 m. Slope inclination: waterside 1:1.5, landside 1:1. Embankment height 0.6 m, width 1.0 m, weight 900 kg. The construction mater-ial included a homogeneous mineral subsoil classified as silty medium sand (siMSa). The embankment model made in a medium-size apparatus kept the accumulation level at a height of 0.5 m. With data from the recording systems, we deter-mined the course of the filtration curve. Next, we kept on loading and relieving the embankment crown using an actuator and a VSS plate with a diameter of 300 mm. During this process, we recorded changes in the level of the water table inside the embankment. A decrease in the water table was observed as a result of increased load. Once the load on the embankment crown was reduced, the water level inside the embankment increased. The embankment model built from natural soil works well as a structure that keeps damming water in a continuous manner. The use of drainage in the form of a stone prism at the foot of the landside slope allows protecting the slope against the negative influence of filtration (piping, lique-faction).

Go to article

Authors and Affiliations

Mariusz Cholewa
Download PDF Download RIS Download Bibtex

Abstract

This article tries to bring more clarity to the issue of media control by the Polish communist party, and in particu-lar identify the institutions, political bodies and politicians who exercised various degrees of control over the press, radio and television in the first half of the 1970. An analysis of various kinds of records and data indi-cates that the day-to-day business of setting the party line for the media was in the hands of propaganda de-partments at the level of the Central Committee. In 1972 they were merged into a single Department of Propa-‑ganda, Press and Publications, headed by Jerzy Łukaszewicz, member of the CC Secretariat, and overseen by Jan Szydlak, member of the Poliburo.
Go to article

Authors and Affiliations

Jacek Wojsław
1
ORCID: ORCID

  1. Instytut Mediów, Dziennikarstwa i Komunikacji Społecznej, Uniwersytet Gdański, ul. Bażyńskiego 4, PL 80-952 Gdańsk

This page uses 'cookies'. Learn more