Design and Development of Three-dimensional Laser Roughness Measurement Apparatus

Rock mass behavior is closely depends on rock joints characteristics, rock joint behavior is depends on its surfaces roughness. There are several methods to measure joint surfaces roughness by two or three dimensional. Three dimensional methods are expensive and advanced technology, thus to obtain high precision roughness of joint surfaces a new apparatus is designed and developed for first time in Iran. Using the designed apparatus the joint surfaces measurement with high precision is possible with low expenses. The apparatus is made up of two parts consisting hardware and software. Hardware consists of: laser head, cross table, and digital camera. The measured data is processed in software to obtain three dimensional surfaces roughness. As an advantageous of the developed apparatus it is possible to determine surface roughness using non-destructive method and same sample could be used for mechanical laboratory testing. To verify the apparatus performance a rock joint specimen roughness profiles is measured with 1mm intervals and the surface topography of joint surface is obtained with 1mm*1mm cell size. In this paper the apparatus assembly and its application along with the results are illustrated

Reflection-based imaging of macular pigment distributions in infants and children

pre-printWe have developed a reflection-based capability of the RetCam® platform, an FDA-cleared pediatric retinal-imaging instrument, for the purpose of measuring macular pigment levels as well as their spatial distributions in infants and children. Our modifications include narrow-band blue-wavelength excitation of the macular pigment absorption in combination with spectrally selective blue-wavelength readout of the reflection signals received by the instrument's CCD detector array. Furthermore, an algorithm is developed that allows the computation of optical density maps for the macular pigment relative to peripheral retinal areas. This made it possible for the first time to directly measure macular pigment levels and their spatial features in the developing human retina. In contrast to adults, infants with measurable pigment levels had almost exclusively a narrow, circularly symmetric, pigment distribution. The described methodology holds promise for future investigations into the role of macular pigment in the developing human retina and the effect of dietary interventions in diseases resulting from a lack of normal carotenoid levels

Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions.

Journal ArticleWe have developed a CCD-camera-based nonmydriatic instrument that detects fluorescence from retinal lipofuscin chromophores ("autofluorescence") as a means to indirectly quantify and spatially image the distribution of macular pigment (MP). The lipofuscin fluorescence intensity is reduced at all retinal locations containing MP, since MP has a competing absorption in the blue-green wavelength region. Projecting a large diameter, 488 nm excitation spot onto the retina, centered on the fovea, but extending into the macular periphery, and comparing lipofuscin fluorescence intensities outside and inside the foveal area, it is possible to spatially map out the distribution of MP. Spectrally selective detection of the lipofuscin fluorescence reveals an important wavelength dependence of the obtainable image contrast and deduced MP optical density levels, showing that it is important to block out interfering fluorescence contributions in the detection setup originating from ocular media such as the lens. Measuring 70 healthy human volunteer subjects with no ocular pathologies, we find widely varying spatial extent of MP, distinctly differing distribution patterns of MP, and strongly differing absolute MP levels among individuals. Our population study suggests that MP imaging based on lipofuscin fluorescence is useful as a relatively simple, objective, and quantitative noninvasive optical technique suitable to rapidly screen MP levels and distributions in healthy humans with undilated pupils

Effects of Joint Spacing on Static Bearing Capacity of Rock Foundations in the case of Punching Failure

In this paper, using distinct element method, static bearing capacity of rock foundations containing one, two or three joint sets is investigated in the case of punching failure. The effect of joint spacing is incorporated in the analyses using a dimensionless factor, named spacing ratio (SR). Different values for SR are selected and variation of bearing capacity versus SR is monitored. Then, the magnitude of SR in which the bearing capacity is not changed significantly, is determined. The findings show that for SR30, joint spacing does not affect bearing capacity, significantly. Hence, SR=30 can be used as a criterion for analysis of rock foundations either as an equivalent continuum or a discontinuous medium. Using this criterion, it will tend to greatly reduce the time required for bearing capacity analysis of rock foundations

Multi-Scale joints roughness characterization using wavelet and shear modeling

Mechanical behavior prediction of rock joints is very important in the rock mechanics. Many models have been proposed to predict the mechanical behavior of joints at which lack of correct evaluation of effective roughness coefficient has been the most important shortage. In this research, each of the upper and lower profiles of joint surfaces is considered as a 2-dimensional wave. Then, multi-scale decomposition based on wavelet theory has been applied studying on asperities. Upper and lower profiles have been combined to produce a composite surface having asperities characteristics of both joint surfaces. Each of the composed wave components (roughness and undulation) has been characterized with statistical quantity of arithmetic mean deviation (Ra). This procedure of characterizing for 2-dimensional waves has been easily extended to 3-dimensional joint surfaces. Conformity in the results of shear and dilation modeling and laboratory tests satisfactorily verifies success of the proposed procedure

Determining radius of influence of the face in EPB shield tunneling by finite difference method

For the purpose of understanding the three-dimensional behavior of face tunnel, a three-dimensional finite difference simulation model, which includes all relevant shield tunneling components and allows for the modeling of the step-by-step construction process of the tunnel advance. The soil-structure interaction in shield tunneling is investigated by numerical solution. The results of three-dimensional ground displacements and stress pattern around a tunnel face and at the ground surface are examined. Results obtained from these analyses indicate that the general threedimensional stress and displacement patterns around a tunnel heading are very different from that at the plane strain transverse section. The distance required for the ground displacement to reach the plane strain condition will depend on the amount of plasticity developed around the tunnel opening. Consequently, face is the most important zone for the design engineer in EPB tunneling

Design Optimization In A Conventional Tunnelling Project In Urban Area Using The Observational Method- Niayesh Road Tunnel In Tehran, Iran

Sharifzadeh, M. and Yasrobi, S. and Ghorbani, M. and Daiyan, M. 2014. Design Optimization in a Conventional Tunnelling Project in Urban Area using the Observational Method-Niayesh Road Tunnel in Tehran, Iran, in Negro, A. and Cecílio, M. and Bilfinger, W. (eds), Proceedings of the World Tunnel Congress 2014 – Tunnels for a better Life, May 9-15 2014, p. 157. Foz do Iguaçu, Brazil: CBT/ABMS

Soil abrasiveness for EPB-TBM along Tehran metro tunnel line 7, Iran

Full-face shielded tunnel boring machines (TBM) including earth pressure balance (EPB) shields have been used almost exclusively for soft ground tunneling because of the many advantages the offer in comparison to the conventional methods. The total number of EPB-TBMs that were utilized for tunneling between 2005 and 2010 is approximately 350 units worldwide as reported by [1]. These machines encounter a wide range of geological conditions and hazards. One of the most critical adverse conditions is encountering abrasive soils and excessive wear on the cutting tools and the cutterhead as has been reported in many EPB tunneling projects worldwide [2], [3]. Inspection and maintenance of cutting tools below the groundwater table is usually performed under hyperbaric conditions where air pressure is used to provide tunnel face stability. This involves creating a plug at the face, removing the spoils (muck), applying compressed air, and allowing the crew into the cutting chamber via an air lock. This entire process can take days to complete. Consequently, the tool inspection and maintenance in soft ground tunneling is a time consuming, risky, dangerous, and costly [4]. Abrasiveness of soil and rock is a factor with considerable influence on the wear of tools. The wear of excavation tools is an important measurable indicator of rock and soil excavation in tunnelling, in addition to the volume of material excavated (Fig. 1). [5]. In mechanized tunneling the term wear is classified into two categories, primary wear and secondary wear. Primary wear is an expected type of wear that can occur on several parts of the excavation tools, such as drag bits, disc cutters, scrapers and buckets, etc. Secondary wear, on the other hand, is an unplanned type of wear that affects the cutterhead spokes, cutter saddles, bulkheads and also much conveyance parts such as the screw conveyor. The first type of wear requires replacement at appropriate intervals whereas the second type is not and therefore the parts are not anticipated to be replaced regularly. As such the TBM performance may be affected significantly if sever secondary wear occurs [6]. In this paper, an investigation was undertaken to discern the main cause of the observed wear on EPB-TBM of Tehran Metro Line 7 (North-South lot). The wear potential of soils and rocks are assessed with respect to approach on the matter was introduced by [5] and Cerchar test, respectively

Uncertain voronoi cell computation based on space decomposition

LNCS v. 9239 entitled: Advances in Spatial and Temporal Databases: 14th International Symposium, SSTD 2015 ... ProceedingsThe problem of computing Voronoi cells for spatial objects whose locations are not certain has been recently studied. In this work, we propose a new approach to compute Voronoi cells for the case of objects having rectangular uncertainty regions. Since exact computation of Voronoi cells is hard, we propose an approximate solution. The main idea of this solution is to apply hierarchical access methods for both data and object space. Our space index is used to efficiently find spatial regions which must (not) be inside a Voronoi cell. Our object index is used to efficiently identify Delauny relations, i.e., data objects which affect the shape of a Voronoi cell. We develop three algorithms to explore index structures and show that the approach that descends both index structures in parallel yields fast query processing times. Our experiments show that we are able to approximate uncertain Voronoi cells much more effectively than the state-of-the-art, and at the same time, improve run-time performance.postprin