Completion of restoration and rehabilitation of the central tailing heap of Jan Šverma mine in Žacléř

In the year 2010, the authors made the reader familiar with the successful implementation of rehabilitation of the Utilization of result of trial seeding experimental plots in the course of rehabilitation of the central tailing heap of Jan Sverma Mine in Zacler by means of the article Rehabilitation of Central Tailing Heap of Jan Sverma Mine in Zacler, [3,5,6,7]. They described briefly the locality of the Jan Sverma Mine and made the reader acquainted with the joint-stock company GEMEC - UNION carrying out the rehabilitation. The authors generally described the restoration and rehabilitation methods [8,9,11] and subsequently the procedure and execution of rehabilitation work on the Central Tailing Heap, namely grassing using the Hydroseeding method. The contribution included the results of trial seeding with the application of various fertilisers and soil conditioners. In this contribution, the authors will focus on the continuation of restoration and rehabilitation works in the west part of the Central Heap. They will be concerned with the evaluation of both overall completion of rehabilitation and subsequent use of the very Heap.Web of Science21213812

One-dimensional photonic crystal for Bloch surface waves and radiation modes-based sensing

We report on a one-dimensional photonic crystal (1DPhC) represented by a multilayer structure used for a surface plasmon-like sensing based on Bloch surface waves and radiation modes employing a structure comprising a glass substrate and four bilayers of TiO2/SiO2 with a termination layer of TiO2. We model the reflectance responses in the Kretschmann configuration with a coupling prism made of BK7 glass and express the reflectances for both (s and p) polarizations in the spectral domain for various angles of incidence to show that a sharp dip associated with the Bloch surface wave (BSW) excitation is obtained in p polarization when an external medium (analyte) is air. For s-polarized wave BSW is not excited and a shallow dip associated with the guided mode excitation is obtained for a liquid analyte (water). For decreasing angle of incidence, the dip depth is substantially increased, and resonance thus obtained is comparable in magnitude with resonance commonly exhibited by SPR-based sensors. In addition, we revealed that the resonances in s-polarization are obtained for other analytes. The surface plasmon-like sensing concept was verified experimentally in the Kretschmann configuration for the guided mode transformed into the radiation mode with a negative and constant sensitivity of -169 nm/RIU, and a detection limit of 5.9 x 10(-5) RIU.Web of Science9104022400

Sensing based on Bloch surface wave and self-referenced guided mode resonances employing a one-dimensional photonic crystal

Sensing abilities of a one-dimensional photonic crystal (1DPhC) represented by a multilayer dielectric structure are analyzed theoretically and experimentally, using a new wavelength interrogation interference method. The structure comprising a glass substrate and six bilayers of TiO2/SiO2 with a termination layer of TiO2 is employed in both gas sensing based on the Bloch surface wave (BSW) resonance and liquid analyte sensing based on a self-referenced guide-mode resonance (GMR). We model the spectral interference reflectance responses in the Kretschmann configuration with a coupling prism made of BK7 glass and show that a sharp dip with maximum depth associated with the BSW excitation is red-shifted as the refractive index (RI) changes in a range of 1-1.005. Thus, a sensitivity of 1456 nm per RI unit (RIU) and figure of merit (FOM) of 91 RIU-1 are reached. Similarly, we model the responses for aqueous solutions of ethanol to show that dips of maximum depth are associated with the GMRs, and the highest sensitivity and FOM reached are 751 nm/RIU and 25 RIU-1, respectively. Moreover, we show that one of the dips is with the smallest shift as the RI changes, and hence it can be used as a reference. The theoretical results are confirmed by the experimental ones when the BSW resonance is used in sensing of humid air with a sensitivity of 0.027 nm/%relative humidity (RH) and FOM of 1.4x10(-3) %RH-1. Similarly, the GMR is used in sensing of aqueous solutions of ethanol, and the highest sensitivity and FOM reached 682 nm/RIU and 23 RIU-1, respectively. The reference dip is also resolved and this self-reference makes the measurement more accurate and repeatable, and less sensitive to optomechanical drifts.Web of Science299130101299

Analysis of several physical phenomena measured on the metallic materials cut by abrasive water jets (AWJ)

Cutting using an abrasive water jet is a complex process involving several physical phenomena. This research studies some of them, mostly the influence of selected variables on the measured forces and vibrations. The traverse speed represents one of the key parameters when cutting using the AWJ. In the presented research, a set of experiments was performed on twelve different metal samples, while the force sensor measured the exerted forces and accelerometers measured the vibrations. Ten different types of steel samples of the same dimensions were cut applying five different traverse speeds. The data obtained during these measurements show that an increase in the traverse speed leads to an increase in the measured forces and vibrations. An analogous experiment performed on bronze and duralumin samples of the same dimensions, having applied higher speeds to compensate for the difference in the material structure and properties, completes the presented data. The most important results of the research are that exerted forces in the z-axis are higher than those in the x-axis, whereas measured vibrations are higher in the x-axis. According to our research, the elemental structure, especially the carbide formation, affects the measured forces and vibrations substantially.Web of Science1521art. no. 742

Notes on the abrasive water jet (AWJ) machining

The aim of the research was to investigate changes of abrasive grains on metals observing the kerf walls produced by the Abrasive Water Jet (AWJ). The microscopy observations of the sidewalls of kerfs cut by the AWJ in several metal materials with an identical thickness of 10 mm are presented. The observed sizes of abrasive grains were compared with the results of research aimed at the disintegration of the abrasive grains during the mixing process in the cutting head during the injection AWJ creation. Some correlations were discovered and verified. The kerf walls observations show the size of material disintegration caused by the individual abrasive grains and also indicate the size of these grains. One part of this short communication is devoted to a critical look at some of the conclusions of the older published studies, namely regarding the correlation of the number of interacting particles with the acoustic emissions measured on cut materials. The discussion is aimed at the abrasive grain size after the mixing process and changes of this size in the interaction with the target material.Web of Science1422art. no. 703

Determination of Physics-mechanical Properties from his Disintegration by Waterjet

Import 11/11/2010Doktorská práce je zaměřena na stanovení vazeb mezi materiálovými vlastnostmi a účinky abrazivního kapalinového paprsku, a je v přímé vazbě k řešení projektu MPO 1H–PK2/22. Existuje řada přístupů k vyhodnocování kvality povrchů vytvořených abrazivním kapalinovým paprskem, ať už se jedná o hodnocení drsnosti, vlnitosti nebo hodnocení stop konvergence či divergence vzniklých na stěnách řezu při průniku paprsku materiálem. Předložená doktorská práce popisuje princip a užití nové metody měřící typické kvalitativní charakteristiky řezání. Metoda je založena na určování míry odklonu abrazivního kapalinového paprsku od původního směru vlivem pohybu trysky nad řezaným materiálem a rozdílných vlastností různých typů materiálů. Tato míra je charakterizována tzv. deklinačním úhlem, parametrem, který je sledován u jednotlivých druhů materiálů s rozdílnými fyzikálně-mechanickými vlastnostmi. Teoretické i experimentální práce byly zaměřeny na zjišťování vztahů mezi parametry použitých kapalinových paprsků a vlastnostmi dostupných zkoumaných materiálů. V teoretické části jsou rozebrány vědecké přístupy autorů zabývajících se problematikou kapalinového paprsku a popsány jejich teorie a soustavy rovnic, umožňující výpočet důležitých parametrů řezání. Nejpodrobněji je rozebrána teorie Hlaváče, ze které tato doktorská práce vychází a zaměřuje se na parametry materiálů obsažené právě v této teorii. Snaha prokázat přímou vazbu mezi velikostmi vybraných parametrů a velikostmi deklinačních úhlů vyžaduje znalost struktury materiálů. Detailnější rozbory struktury a vlastností se provádí na specializovaných pracovištích, která pomocí většinou normovaných předpisů vyberou a použijí metodu vhodnou pro stanovení požadované vlastnosti. Materiálové vlastnosti byly zpravidla takto stanovovány. Praktická část je zaměřena na dvě skupiny materiálů – kovy a horniny. Přesto,že tyto dvě skupiny zahrnují v reálu velké množství zástupců, do experimentů bylo zařazeno pouze omezené množství materiálů, které byly vyselektovány požadavky rozměrové shodnosti, která byla nutná pro vyhodnocení porušení provedeného kapalinovým paprskem. Při tomto postupu jsou konfrontovány vybrané vlastnosti daného materiálu získané z různých zdrojů. Byla hledána přímá vazba mezi velikostí naměřeného deklinačního úhlu, který je vypovídajícím parametrem kvality řezaného povrchu, a velikostí jednotlivých materiálových vlastností a jejich kombinací. Získané poznatky mohou vést ke zlepšení účinnosti a efektivity samotného řezného procesu a byly použity při vývoji nového řídícího programu CNC strojů nové generace v PTV spol. s r.o. Hostivice.Thesis are aimed at determination of correlation between material properties and effects of abrasive water jet, and it is in a direct relationship with solving of the project MPO 1H–PK2/22. There is a range of approaches to the evaluation of quality of surfaces created by the abrasive water jet, from the ones evaluating the roughness and waviness to the ones evaluating the convergence or divergence established on the surface of the cut during penetration of jet through material. The presented doctor’s dissertation describes the principle and use of a new method of measuring the typical quality characteristics of the cut. The method is based on establishing the scale of deviation of the abrasive water jet from the original direction due to the movement of the nozzle over the cut material and different qualities of the various materials. This scale is characterised by the so-called declination angle, the parameter which is monitored by the individual sorts of materials with different physical-mechanical qualities. Theoretical and experimental works have established the relationship between the parameters used with liquid jets and the qualities of the accessible tested materials. In the theoretical part I have discussed the scientific approaches of authors dealing with the problem of water jet and I have described their system of equations which enabled evaluation of the important parameters of cutting. I have focused in most detail on Hlaváč’s theory, as these theses are mainly based on, and I concentrated on the parameters of materials included in this theory. The effort to prove a direct correspondence between values of selected parameters and values of angles of declination demanded certain knowledge of the material structures. More detailed analyses of the structure and qualities are conducted at specific work stations that using mostly standardised directives, select and use a suitable method for determining of the required quality. The practical part is focused on two groups of materials – metals and rocks. Although both these groups include a large number of representatives in fact, only a limited number of materials have been incorporated into the experiments. They had been selected based on the requirements for cutting by the water jet and on the consequent evaluation of results aimed at prove of a possible correlation. I have also confronted their selected qualities obtained from various sources. A direct relationship connected to the measured declination angle is looked for being a predicative parameter of the quality of the cut surface. The acquired knowledge can lead to improvement of the efficiency and effectiveness of the cutting process itself and has been used for the development of the new CNC control program of machines of a new generation in the PTV spol. s.r.o. company in Hostivice.Prezenční516 - Institut fyzikyvyhově

Elaboration and properties of fly ash based microfiltration membrane support

The main aim of this work was to prepare a ceramic membrane support applied directly to microfiltration of industrial wastewater using a simple and cheap method. Microfiltration (MF) supports were prepared using fly ash as a dominant material and by addition of natural inorganic materials kaolin and claystone. These powders were mixed with alkali solution in order to prepare paste suitable for extrusion. The extruded tubes dried at room temperature and sintered at 1000°C showed great chemical resistance. Their morphology was examined by scanning electron microscope (SEM) and showed a homogeneous porous structure without any cracks. The average pore size distribution of the tubes was about 2 μm and pore volume was 33%. Fabricated MF membrane supports were tested using the cross-flow microfiltration process. Results with distilled water showed permeability of 680 l/h m 2 bar that is comparable with commercial one

Notes on the Abrasive Water Jet (AWJ) Machining

The aim of the research was to investigate changes of abrasive grains on metals observing the kerf walls produced by the Abrasive Water Jet (AWJ). The microscopy observations of the sidewalls of kerfs cut by the AWJ in several metal materials with an identical thickness of 10 mm are presented. The observed sizes of abrasive grains were compared with the results of research aimed at the disintegration of the abrasive grains during the mixing process in the cutting head during the injection AWJ creation. Some correlations were discovered and verified. The kerf walls observations show the size of material disintegration caused by the individual abrasive grains and also indicate the size of these grains. One part of this short communication is devoted to a critical look at some of the conclusions of the older published studies, namely regarding the correlation of the number of interacting particles with the acoustic emissions measured on cut materials. The discussion is aimed at the abrasive grain size after the mixing process and changes of this size in the interaction with the target material

Interaction of various types of rock and alkali-activated blast furnace slag

Alkali-activated binders (AAB) are very intensively studied materials nowadays. Because of possible usage as secondary raw materials, they can be environmentally efficient. Intensive research is focused especially on binder matrix, composition and its structure. For industrial usage, it is necessary to work with some aggregate for the preparation of mortars and concretes. Due to different structures of alkali-activated binders, the interaction with the aggregate will be different in comparison to an ordinary Portland cement binder. This paper deals with the study of interactions between several types of rocks used as aggregate and alkali-activated blast furnace slag. The research was focused especially on mechanical properties of prepared mortars

Interfacial Transition Zone Between Aggregate And Alkali-Activated Blast Furnace Slag – A Scanning Electron Microscopy

Alkali-activated binders are currently a widely-researched material. Thanks to the use of secondary raw materials such as slag from metallurgical production and ash from combustion, it appears to be a more promising and more environmentally friendly material than conventional cement concrete. Considerable attention is paid to the bonding phase itself, but only a few works deal with the binder-aggregate interaction. With cement concrete, much more attention is paid to this issue. This paper deals with the possibility of observation using electron microscopy and the information that can be obtained by this method. The problems of sample preparation and difficulties in the course of our own observation are observed