Three-dimensional Laser Scanning Technique Research Articles

Quantitative Assessment of Upper-Limb Volume: Implications for Lymphedema Rehabilitation?

Upper-limb lymphedema is a chronic condition characterized by the accumulation of lymphatic fluid in the arm or hand, resulting in swelling and functional impairment. The accurate and reliable volumetric assessment of limb volume is crucial for the correct management of lymphedema. This narrative review provides an overview of the different methods proposed in the literature for the volumetric assessment of upper-limb lymphedema. In more detail, several methods of volumetric assessment have been proposed in recent years, including water displacement, the centimetric method, perometry, bioimpedance spectroscopy, dual-energy X-ray absorptiometry, magnetic resonance imaging, computed tomography, and three-dimensional laser scanning techniques. On the other hand, each method is characterized by specific strengths and limitations in terms of accuracy, reliability, practicality, and cost-effectiveness. Moreover, factors including operator experience, equipment availability, and patient population characteristics might have several implications in the optimal assessment of upper-limb volume. In this context, a precise volumetric assessment is crucial to improving the rehabilitation framework, patient education, and research outcomes. As a result, the integration of emerging technologies is needed to improve the tailored management of patients with upper-limb lymphedema. In conclusion, volumetric assessment methods provide valuable insights in the management of upper-limb lymphedema, improving patient care, treatment outcomes, and research advancements. Future research should focus on testing these innovative solutions on larger samples of patients to enhance the reproducibility, accuracy, accessibility, and clinical utility of volumetric assessment methods in the complex treatment framework of upper-limb lymphedema.

Cataclastic Characteristics and Formation Mechanism of Dolomite Rock Mass in Yunnan, China

The dolomite rock mass on the slope of the Yanhe domestic waste incineration power plant was used as the research object. The macro- and micro-structural characteristics of intact rock blocks and rock discontinuities were analyzed qualitatively and quantitatively using in-hole television, wave velocity testing, three-dimensional laser scanning techniques, photogrammetry, image processing techniques, and scanning electron microscopy (SEM). The study shows that the degree of fracturing generally decreases with depth over the exposed borehole depth range, and the rock masses are generally very fractured. The wave velocity of dolomite generally increases with the depth of the borehole, and the integrity of the dolomite is either broken or extremely broken. The excavation profile reveals six sets of discontinuities and joints that are straight, smooth, interconnected, and largely unfilled. The angles of the structural bodies of different grain sizes are sharp, with roundness being angular and sharp-angled. The smaller the blocks, the more complex the surface morphology. SEM observations show that the ultramicroscopic fractures are not flat and smooth, and the fractures are folded. Fracturing mainly occurs along intercrystalline and crystal interfaces. These fracture features suggest that the fracturing of dolomite is mainly related to the original sedimentary construction and tectonism.

On the methods of recognition and classification of laser reflection points based on the Terrasolid software module on the Bentley Microstation platform

Nowadays, the use of the three-dimensional laser scanning technique in performing various scientific research comes to the fore, since this technology is one of the most developed and effective methods for analyzing the state of transport infrastructure objects and geodetic monitoring. The purpose of this paper is to develop an author’s algorithm for the classification of laser reflection points, based on the specialized Terrasolid software on the Bentley Microstation platform. The object of the research is the campus of the territory of the Federal State Budgetary Educational Institution of Higher Education “Kuban State Technological University”. The subject of the research is the possibility of optimizing the process of classification of laser reflection points on the campus of the university territory. The result of the study is the author’s algorithm for the classification of laser reflection points.

Experimental and numerical investigation of jointed self-centering concrete walls with friction connectors

A jointed self-centering (SC) concrete wall system with friction connectors is proposed, in which the precast concrete wall panels are assembled through unbonded posttensioning (PT) tendons to provide self-centering capacity, and friction connectors at the vertical joint provide supplementary energy dissipation as the walls move relatively to each other during a major earthquake. The wall toes are protected by the steel jackets from crushing as the walls rock. The behavior of the jointed wall system was experimentally investigated through nine cyclic load tests, based on which the influence of different initial PT forces and friction forces on structural performance of the walls was discussed. Besides, strains on the steel jackets during the tests were measured to validate the effectiveness of steel jackets, and three-dimensional laser scanning technique was applied to measure the in-plane and out-of-plane deformations of the walls. It is observed that the main structure remained resilient after the nine tests with the maximum drift ratio of about 2.98%, though cracking in concrete cover at the eastern connectors was found after a number of reversal loading, which calls for improved structural details. A numerical simulation method of the jointed SC wall system is proposed, and the simulated hysteretic behaviors match well with the test results.

REFINED MODELING OF COMPLEX GEOLOGICAL BODY BASED ON THERE-DIMENSIONAL LASER SCANNING TECHNIQUE

In the platform of FLAC3D software, how to build the three-dimensional models of complex geological bodies is always a difficulty encountered by many numerical simulation operators. On the other hand, the three-dimensional laser scanning technique presents a unique advantage in obtaining the fine spatial data of complex objects. Therefore, by the aid of reverse engineering, a new modeling method of complex geological bodies in FLAC3D platform is proposed. The accurate spatial and geometric information of complex geological bodies is firstly obtained by employing three-dimensional laser scanning technique. The point cloud data describing surface characteristics of complex geological bodies is processed and its surface model is then reconstructed in CAD format. Using the formidable geometry cleanup and mesh generation function of Hypermesh software, the surface model is transformed into three-dimensional finite element model. The node and element information can be translated into the format which can be received by FLAC3D. According to the above processes, the model data for FLAC3D is generated and the refined model of complex geological bodies is created in the pre-processing of FLAC3D.the feasibility and practicability of this approach is verified by combining practical project.

Macro–meso failure mechanism of soil–rock mixture at medium strain rates

Uniaxial compressive strength experiments at medium strain rate were conducted to characterise rate effects and the macro–meso failure mechanism of a soil and rock mixture (SRM) with different rock block percentages using a servo-hydraulic variable frequency dynamic machine. Macroscopic failure morphology descriptions and meso three-dimensional laser scanning techniques are used to investigate internal failure mechanism. The results indicated that SRM specimens experience splitting failure, shear failure and conical failure with increasing strain rate. The cumulative fracture width and surface toughness were dependent on the loading rate, which were the results of interaction between rock blocks and the soil matrix and induced by the intrinsic fracture mechanism.

Fatigue behavior of corroded prestressed concrete beams

This paper presents the results of an experimental study on the fatigue behavior of pretensioned partially prestressed concrete beams with corroded prestressing wires or rebars. A three-dimensional laser scanning technique was employed to obtain the geometric models of corroded prestressing wires or rebars. It was observed that fatigue cracks initiated and propagated rapidly around corrosion pits under cyclic loading. The cyclic loading led to fatigue fracturing of the prestressing wires (rebars) at the minimum cross-section where the corrosion pits had formed. With the increased corrosion of the prestressing wires, the sooner fracture of the first wire and the shorter interval between the failures of the two wires in the test beam were found, resulting in a shorter fatigue life of the beam. A higher partially prestressed ratio or load range brought a larger stress level, stress range, and thus a shorter fatigue life of corroded beams. Compared with the uncorroded beam, it was also found that the corroded beams exhibited a faster stiffness degradation and development of deflections and crack widths under cyclic loading.

Geological 3D modeling for excavation activity in an underground marble quarry in the Apuan Alps (Italy)

The three-dimensional laser scanning technique has recently become common in diverse working environments. Even in geology, where further development is needed, this technique is increasingly useful in tackling various problems such as stability investigations or geological and geotechnical monitoring. Three-dimensional laser scanning supplies detailed and complete geometrical information in short working times, as a result of the acquisition of a large number of data-points that accurately model the detected surfaces. Moreover, it is possible to combine these data with high quality photographic images so as to provide important information for geological applications, as follows. A working approach, that combines terrestrial laser scanning and traditional geological surveys, is presented. A three-dimensional model, that includes information about the geological structure in an underground quarry in the Apuan Alps, is realized. This procedure is adaptable to other geological contexts, and because of its operating speed and accuracy it is invaluable for optimal excavation, in which a proper planning of quarrying activity is vital for safety and commercial reasons.

Probability Distribution Model for Cross-Sectional Area of Corroded Reinforcing Steel Bars

This paper presents the development of a probabilistic model for the cross-sectional area of corroded reinforcing steel bars (rebars), in order to assess the time-dependent reliability of corroded reinforced concrete (RC) structures. The indicator R, which is the ratio of the average to the minimum cross-sectional areas of corroded rebars, was adopted to quantify the longitudinal variation of the cross-sectional area. By using a three-dimensional laser scanning technique, the areas of the discrete cross-sections were evaluated along the length of a rebar at intervals of 1 mm. The statistical results showed that R could be characterized by the Gumbel distribution. Both the location parameter and the scale parameter for the probability distribution of R increased linearly with increases in the corrosion degree and were dependent on the element length and the diameter of the corroded rebar. The results of a time-dependent reliability analysis of corroded RC beams demonstrated that an element length of 150 mm should be chosen for reliability assessment and that larger diameter rebars should be chosen for structural design when the reduction of load bearing capacity caused by corrosion of rebars needs to be considered.

Three-dimensional laser scanning technique to quantify aggregate and ballast shape properties

There is a need to improve the measurements of shape characteristics of aggregates and ballast materials used in the construction of road, airfield, and railway track infrastructures. The fundamental shape properties of aggregate and ballast, including form (roundness, flatness, elongation, sphericity), angularity, and surface texture (roughness) have not been accurately quantified because of their irregular and non-ideal shapes. Current developments are shifting from manual and subjective methods towards a more accurate and automated techniques to quantify aggregate shape properties. This paper validates a new flakiness index equation using three-dimensional (3-D) laser scanning data of aggregate and ballast materials obtained from different sources (quarries) in South Africa. The new equation uses volume ratio instead of the traditional mass ratio to determine flakiness index of aggregates and ballast materials. It is concluded that the validated equation can be used with confidence to determine flakiness index of aggregate and ballast materials.

Cell shape effect evaluation of polyamide cellular structures

The paper describes an experimental investigation of regular open-cell cellular structures, where the influence of cell shape on cellular structure behavior under uniaxial compressive loading has been studied. Cellular structures with circular and quadratic cells have been manufactured with the laser sintered rapid prototyping technique using polyamide PA-12 as the base material. An advanced approach for Poisson’s ratio evaluation is proposed, which is based on the three-dimensional laser scanning technique. The experimental results have shown that the same layer-wise collapse mechanism, commonly observed in irregular open-cell structures, can be observed also in regular open-cell structures. The energy absorption characteristics show advantageous performance of cellular structures with circular cells in comparison to the quadratic cells.

Investigation and correlation of manikin and bench‐scale fire testing of clothing systems

AbstractThe US Army currently has five flame/thermal protective clothing systems to provide protection for soldiers against fire hazards. The protective performance of these clothing systems against burn injuries was investigated in full‐scale manikin tests. The protective performance of fabric layers of these clothing systems was also examined in bench‐scale tests. In addition, air gap thicknesses and distributions of the five clothing systems were determined by using a three‐dimensional laser scanning technique. In this paper, test conditions of the manikin and bench‐scale tests are compared, and the test results are correlated in light of the air gap measurements. The behavior of individual sensors on the manikin with similar test conditions to those of bench‐scale tests are compared with the bench‐scale tests. It is found that if the air gap distribution of a clothing system is known, bench‐scale tests could provide useful information for full‐scale performance, especially bench‐scale tests with zero air gap measurements. Published in 2002 by John Wiley & Sons, Ltd.