History of Passive Pressure of Non-Cohesive Mass and Its Consequences for Theory of Earth Pressure

Recently, the long-term research of passive pressure has been carried out. The rotation about the toe of the physical model sized 3.0*1.0*1.2 m has brought unexpected results similarly as the previous research of active pressure. The research contains among others the investigation of time stability of both pressure components, i.e. normal component and shear component. The paper presents latest information about physical modelling and its results and compares the results with the concept of the developed the General Lateral Pressure Theory (GLPT). This theory is supported also by the monitored time instability of lateral pressure, which is discussed as well. The recent state of the General Lateral Pressure theory in contradiction to the state of the recent earth pressure theory is mentioned

History of Ultimate Limit State of Bored Piles

In European Union, the basic geotechnical code EUROCODE 7 - Geotechnical design, Part 1 - General rules (EC7-1) has been finished and its National Annexes have been drafted. The designs according to both EC7-1 and the Czech basic standard ČSN 73 0031 “Structural reliability – Basic requirements for design” are based on the Limit State Design theory. However, there is a principal difference between the inputs according to EC7-1 and the inputs according to ČSN 73 0031. In general, the input difference results in too conservative (ineffective) designs according to EC7-1 and more effective (more optimistic) designs according to ČSN. Due to these differences analyses of slopes, shallow foundations and earth pressure concepts have been carried out and an analysis of pile design appears necessary, too. The Paper shows briefly the history and development of the Ultimate Limit State Design of bored piles. Attention focuses on a comparative analysis of the tabular design values and the results of numerical analysis and their suitability for the Czech National Annex of EC7-1. The analysis results are compared with tabular design values of the relevant Czech standard

Case of Ultimate Limit State Design and Eurocode 7-1

The history of the Limit State Design (LSD) in geotechnics is rather long. The first attempt to implement the semi-probabilistic design method in geotechnics was published probably by Brinch Hansen in 1953. This theory was implemented formally in Czech practice in 1966 but it was opposed by most professionals. The theory was contrary to the former successful Safety Factor Design and objections were targeted especially against the Ultimate Limit State Design (ULSD). The development of Eurocode (EC) 7-1 began at the end of 1970 and met with similar opposition. However, the same problem was solved in a different way with the Czech standardization which had implemented the LSD with another definition of characteristic input values. The European standardization retained the classical LSD including geotechnical ULSD although design problems were not solved satisfactorily. Now, EC 7-1 has come into force in the European Union (also in the Czech Republic) and it is in a period of calibration. The most serious problem is the ULSD application for geotechnical (non-linear) tasks using derived material inputs which appear to be very inadequate. It appears to be it necessary to check the base of the ULSD theory. The paper presents results and conclusions of the problem analyses

Granular Mass Behaviour under Passive Pressure

Actual behaviour of the soil/granular mass under lateral/earth pressure is highly complex and has not been sufficiently described and known to data. In this paper the term Lateral pressure is used instead of the customary earth pressure to differentiate a new theoretical approach to the problem and because the term lateral pressure appears more adequate and less general in this particular problem. A significant characteristic of lateral pressure consists in its continuous variability in time. For this reason a number of objections may be raised against the contemporary earth pressure theory. The paper sums up the present state of knowledge and a new theory acquired by research. It shows the real non-cohesive mass behaviour under passive pressure

Double Case of Passive Pressure Acting on Wall Rotated About the Top

Basic research of lateral earth pressure based on physical and numerical experiments began in 1998 at the institute of the author and it has continued to the present time. The physical research should prove the behavior of ideally non-cohesive granular mass during three basic types of structure/wall movement towards in active and passive directions. The first research period in 1998-2000 was aimed on active pressure, and in 2001-2002 on the first long-term experiment with passive pressure (E3/0.2). Then new experimental equipment was developed between 2003 and 2009 on a contemporary advanced level. The first long-term experiment with passive pressure E3/0,2 acting on a wall rotated about the top was repeated and as double same long-term experiments, denoted as experiments E5/0,2 (2010) and E6/0,2 (2011). The new equipment is completely under computer control and it has five bi-component pressure sensors in the arbitrarily moved front wall and six sensors in the solid back wall. The velocity of the front wall movement can be arbitrarily slow from of 3.684 to of \u3e0 mm/min, the maximal pushing force being about of 2870 kN. The maximal recording frequency is of 1000 Hz and it can accommodate a huge quantity of data of 803 MB/day. The paper presents proof that theoretically considered passive pressure of ideally non-cohesive material on a wall rotated about the top cannot be achieved

A Variational Formulation for Classical Models of the Slope Stability With Earthquake Effect

The paper deals with an extension of application of the Method of Apriori Integration to a model of a general slope, which is partly homogeneous and which is loaded also by the earthquake effect. The most dangerous direction of the power effect of the vibration is shown and for this direction the change of safety factor is discussed. The effect of reduced shear strength is included

Study of the Indoor Optical Wireless Network in the Visible Optical Radiation

Import 02/11/2016Bezdrátové datové sítě představují progresivně se vyvíjející oblast informačních technologií. Umožňují lidem být více flexibilní, protože nemusí zůstat v pevném místě, například doma nebo v kanceláři, ale mohou sdílet informace s ostatními lidmi při cestování v autě nebo při chůzi po ulici. Bezdrátové datové sítě umožňují lepší dostupnost služeb než tradiční drátové připojení. Nový dynamický směr vývoje bezdrátových datových sítí je založen na myšlence datových sítí využívajících optického záření v oblasti viditelného spektra VLC (Visible Light Communications). Impulzem tohoto směru vývoje se stal pokrok v technologiích polovodičového osvětlení prostřednictvím bílých výkonových LED (Light Emitting Diode). Tento typ bezdrátových datových sítí označujeme jako optické bezvláknové datové sítě pro vnitřní prostory využívající optického záření v oblasti viditelného spektra. První výsledky výzkumu v této oblasti byly zakončeny v prosinci 2011 normou IEEE 802.15.7 (modulační formáty OOK, VPPM a CSK). Práce si klade za cíl sledovat současné trendy pokračujícího výzkumu. Jedná se o problematiku vícecestného šíření při hybridním spojení mezi vysílačem a přijímačem při přímé viditelnosti LOS (Line of Sight) a řešení kolísání včetně řízení optického výkonu při přenosu dat pro vícestavové modulační formáty. Teoretická část práce se zabývá problematikou matematického popisu a softwarového modelování buňky optického vysílače pracujícího ve viditelné oblasti optického záření a dále matematickému popisu vlivu modulačních formátů na problémy způsobené vícecestným šířením. Praktická část práce se věnuje experimentálnímu ověření vlivu modulačních formátů na problémy způsobené vícecestným šířením, ověřením vlivu modulačních formátů na kolísání optického výkonu včetně návrhu řešení eliminace kolísání a řízení optického výkonu pro vícestavové modulační formáty.The wireless networks represent progressively developed area of information technologies. They allow to the people to be more flexible, because they can’t be fixed in their homes or offices, but they can share information with other people during travelling in the train, car or even during walking on the street. The wireless networks enable better availability of the services then conventional wiring connection. The new dynamic direction of wireless networks development is based on the idea of networks utilizing the optical radiation in the visible spectrum VLC (Visible Light Communications). The impulse of this development direction was improvement in the semiconductor lighting technologies, namely the white power LEDs (Light Emitting Diode). These types of wireless networks are denoted as the optical wireless networks for indoor spaces utilizing optical radiation in the visible spectrum. The first research results in this area were concluded by the IEEE standard 802.15.7 (modulations VPPM, OOK and CSK) in 2011. The aim of this thesis is to observe current research trends. It is mainly problematic of multipath propagation during hybrid connection in between transceiver and receiver with direct visibility LOS and variation of optical power during data transmission for higher modulation formats. The theoretical part of this thesis includes summary of wireless networks, is closely dealing with optical wireless networks and also with mathematical description of optical wireless networks channel for indoor spaces utilizing optical radiation in visible spectrum. The theoretical part is dealing with mathematical description and software modulation of the optical transmitter cell operating in visible radiation range and also with mathematical description of the modulation formats influence on difficulties caused by multipath propagation. Practical part is aimed at experimental verification of modulation formats influence on problems caused by multipath propagation, verification of modulation formats influence on optical power variation. This part is also including suggestions for variations elimination and optical power control in case of multistate modulation formats.440 - Katedra telekomunikační technikyvyhově

NUMERICAL MODELLING OF WAVE SHAPES DURING SHPB MEASUREMENT

The paper aims at the numerical simulation of the wave propagation in compressive Split Hopkinson Pressure Bar (SHPB) experiment. The paper deals with principles of SHPB measurement, optimisation of a numerical model and techniques of pulse shaping. The parametric model of the typical SHPB configuration developed for LS-DYNA environment is introduced and optimised (in terms of element size and distribution) using the sensitivity study. Then, a parametric analysis of a geometric properties of the pulse shaper is carried out to reveal their influence on a shape of the incident pulse. The analysis is algorithmized including the pre- and post-processing routines to enable automated processing of numerical results and comparison with the experimental data. Results of the parametric analysis and the influence of geometric properties of the pulse shaper (diameter, length) on the incident wave are demonstrated

Restoration of optical spectrum

This article deals with research of luminous sources which could be applied in indoor Free Space Optic (FSO) networks. Indoor FSO networks have potential to replace standard IEEE 802.11 in the future. Suitable selection and configuration of optical radiation sources can at the same time provide communication and lighting in indoor spaces. This article is engaged in spectral mergence of optical sources, willful suppression of part of emitted visible spectrum and consequential restoration of this optical spectrum

MULTI-CHANNEL CONTROL SYSTEM FOR IN-SITU LABORATORY LOADING DEVICES

In recent years, open-source applications have replaced proprietary software in many fields. Especially open-source software tools based on Linux operating system have wide range of utilization. In terms of CNC solutions, an open-source system LinuxCNC can be used. However, the LinuxCNC control software and the graphical user interface (GUI) could be developed only on top of Hardware Abstraction Layer. Nevertheless, the LinuxCNC community provided Python Interface, which allows for controlling CNC machine using Python programming language, therefore whole control software can be developed in Python. The paper focuses on a development of a multi-process control software mainly for in-house developed loading devices operated at our institute. The software tool is based on the LinuxCNC Python Interface and Qt framework, which gives the software an ability to be modular and effectively adapted for various devices