Vertical Wall Surface Research Articles

Non-Destructive Methods for Assessing the Condition of Reinforcement Materials in Soil

A reinforced earth wall is a structure in which reinforcement materials are placed in an embankment to build a vertical or nearly vertical wall surface. Such walls have been widely used in roads and in developed land since around 1960. Reinforcement materials have a set service life of 100 years and fall into two types: steel and geosynthetics. To ensure long-term durability, steel reinforcement materials are plated, while geosynthetics are designed with a limit strength designed to resist fracture for 100 years under the conditions of a given load placed on the reinforcement materials. However, owing to the difficulty of assessing the condition of reinforcement materials in soil, this paper proposes solutions based on non-destructive methods. Specifically, it proposes a method of assessing the amount of strain through an embedded optical fiber in the case of geosynthetic reinforcement materials, or magnetic surveying to investigate the degree of corrosion in the case of steel reinforcement materials. This paper demonstrates that it is possible to non-destructively assess the state of either type of reinforcement material.

Effect of Pre-Swirling Flow on Performance and Flow Fields in Semi-Opened Axial Fan

In this study, we tried to improve the performance by giving a pre-swirling flow to the radial inflow that occurred in the semi-opened axial fan. In addition, the flow fields of rotor outlet were clarified experimentally, and the effect of pre-swirling flow was considered. The experiment was carried out using a performance test wind tunnel with a square cross section of 880 mm. Three types of casings were prepared, in which the blade tip protruded 0%, 20%, and 40% of the meridional chord length. They were called R25, R15, and R05, respectively, in the casing bellmouth model code. Guide blades for generating a pre-swirling flow were installed on the vertical wall surface of the casing. In addition, a vertical wall was installed 60% upstream of the meridional chord length as an obstacle to prevent axial inflow. The velocity fields of the rotor outlet were measured using a hot-wire anemometer. From the results, the pre-swirling flow did not significantly affect the fan performance. When there was no obstacles wall upstream, there was a partial increase in efficiency, but the difference was not so large. When there was an obstacle wall upstream, the efficiency increased overall in the case of R15, but in the case of R05, the efficiency increased only in the low flow rate region, and conversely decreased in the high flow rate region. By observing the blade outlet flow fields when the performance was improved, it was confirmed that the influence of the tip leakage vortex was weakened.

Exploring the duality of powder adhesion and underlying surface roughness in laser powder bed fusion processed Ti-6Al-4V

As-built surface roughness remains a significant barrier to widespread uptake of Laser Powder Bed Fusion (LPBF). To overcome this barrier, it is first necessary to understand the structure of this surface. This research explores the duality of the LPBF surface consisting of: 1) an apparent surface dominated by adhered powder and 2) the underlying profile defined by the fully consolidated material.An array of cuboidal specimens were produced by LPBF with varying contour scan parameters to study their influence on the vertical wall surface. For the first time, optical image analysis was used to quantify the extent and size distribution of surface adhered powder particles. SEM micrographs of the sectioned specimens were used in conjunction with a second novel image processing technique to study the underlying surface profile. Researchers utilised these methods to study the relationship between process parameters and both surface topographies. These results were compared against traditional line of sight roughness measurements.Surface finish (Sa), powder adhesion, and underlying roughness decreased with energy input to a point where the contour melt track was observed as unstable and incoherent (~0.1 J/mm). A 19.9 % reduction in Sa was demonstrated by the smoothest specimen (Sa, 10.9 μm) when compared to the control (Sa, 13.6 μm). Argon crossflow within the process chamber was shown to influence the underlying roughness, Ra, with upstream values 4.0 μm lower on average than downstream over most of the experimental range.Adhered particle size showed a finer distribution compared with the feedstock (D50 Surface = 20.8 μm; D50 Feedstock = 32.9 μm). Consequently, a further study comparing specimens built using coarse (sieved to >36 μm, D50 = 42.8 μm) versus fine (sieved to <36 μm, D50 = 28.8 μm) powder was performed. Mean Sa for coarse powder specimens was 1.66 μm greater than fine. However, coarse powder specimens showed fewer surface adhered particles due to geometric packing. Feedstock powder size fraction showed relatively little influence on underlying roughness.Further discussion of particle adhesion mechanics is presented alongside practical processing implications. Finally, the authors suggest that continued research into the duality of the LPBF surface is necessary to not only improve the as-processed material, but to guide future development post-processing treatments.

A Path-Planning Method for Wall Surface Inspection Robot Based on Improved Genetic Algorithm

A wall surface inspection robot mainly relies on the inertial measurement unit and global positioning system (GPS) signal during intelligent wall surface inspection. The robot may encounter incorrect positioning under a GPS-denied environment, easily triggering safety accidents. In order to obtain a path suitable for the safe work of the robot wall surface inspection robot in a GPS-denied environment, a global path-planning method for wall surface inspection robots was proposed based on the improved generic algorithm (GA). The influencing factor for GPS signal strength was introduced into the heuristic function in path planning for GA to address the aforementioned problem. Using the PSO algorithm, GA was initialized and the influencing term of GPS signal was introduced into the fitness degree function so as to achieve point-to-point path planning of vertical wall surface inspection robot. Path angle and probability of intersection and variation was taken into account for better path planning capability. Finally, the simulation experiments were performed. The generated path using the improved GA was found to avoid the blind area of the GPS signal. The algorithm proposed has a good performance with average convergence times of 35.9 times and an angle of 55.88° in simple environment. Contrary to the traditional GA and PSO algorithm, the method showed advantages in terms of the convergence rate, path quality, path angle change, and algorithm stability. The research presented in this article is meaningful and relatively sufficient. The simulation test is also quite convincing. The proposed method was proved to be effective in global path planning for a wall surface inspection robot.

Analysis and experimental research on motion stability of wall-climbing robot with double propellers

This paper presents a wall-climbing robot which can stably hold and move on the ground-wall surface. The robot uses propeller reverse thrust as an adsorption force and can adapt to the surface of several media materials. The influence of the robot’s structural parameters on its power system is analyzed by comparing a single power system test and a robot prototype power test. A structural analysis of the robot is performed under two specific situations; when he is in transition from the ground to a small slope, and when he is on the slope. The force state of the robot is then obtained in different conditions. Experimental results show that the adjustment range of different rotor inclination angles of the robot, the width of the fixed rotor plate and the different near-ground distances, affect the traction of the robot. The robot motion performance and adaptability under different ground/wall environments are analyzed, by conducting the robot climbing experiment under a small slope, a vertical wooden wall surface and a vertical indoor wall surface. Stable adsorption and optimization tests are also performed. Moreover, the stability of the robot’s motion is verified. Finally, a theoretical and experimental accumulation is laid for the realization of the smooth transition of the robot from the ground to the wall.

Rectification of a large vertical wall surface for flatness

This paper describes the efforts made in rectifying a large prestressed, L-shaped, vertical reaction wall with circular cavities and the lessons learnt. The wall was to be constructed with a certain flatness requirement, which it later turned out was not met. Though various studies have been undertaken in the past describing rectification of horizontal concrete floors, the present study discusses a novel approach to determine the extent of non-compliance and then re-surfacing of the vertical wall to achieve required flatness. The paper discusses in detail the applicability of various instruments like profilometers, water level manometers, and laser-based tools in determining the extent of undulations. It was found that the rotating laser-based tool best served the purpose for defect identification and that placing a layer of micro concrete along with a bonding agent using a novel construction method helped to achieve the desired level of flatness.

Wall-climbing obstacle-avoiding full-automatic lampblack cleaning device

With the development of Chinese society and the progress of productive forces, dust and oil stains are easily produced in kitchens and ceilings when living at home. Dirt deposition in many places cannot be carried out well due to the limitation of space location and cleaning methods, which brings great inconvenience to people’s life. At the same time, the existing cleaning robots in the market need to work on a single wall surface, and when encountering obstacles, the positions of the robots need to be adjusted manually to further realize the work and cannot solve the cleaning problems of ceilings and the like. The existing cleaning robots mostly use centrifugal fans to fix on vertical wall surfaces in an adsorption way, thus causing obstacles to be avoided, the connection between different wall surfaces cannot be realized, and the defect that intelligence works on a single wall surface requires manual wall surface replacement, thus reducing automation, intelligence and intelligence. Based on the above background, the members of this group have designed a wall-climbing cleaning machine. The device mainly comprises a walking module, a wall turnover module and a cleaning module [1].

Investigation of mechanics and machinability of titanium alloy thin-walled parts by CBN grinding head

A force model of machining TC4 titanium alloy thin-walled part is developed based on the actual geometry and abrasive characteristics of CBN grinding head in this paper. Then, the single factor experiment illustrates that the grinding force increases with the increase of the grinding depth and feed rate, while it decreases with the increase of the spindle speed. And the contrast experiment results show that new improved grinding head is beneficial for reducing the force compared with common grinding head. On the basis of the mechanics analysis, the chatter stability of grinding thin-walled parts is studied based on the modal tests of titanium alloy thin-walled parts and grinding head, and the stability lobe diagrams are finally drawn as well by considering the radial grinding depth. In addition, further research indicates that the surface roughness of vertical side wall surface and surface micro-hardness is determined by several key parameters including spindle speed, feed rate, and cutting depth in grinding process based on analysis of experiments. An optimal combination of these parameters is of great benefit to achieving better surface of the parts.

AnyClimb-II: Dry-adhesive linkage-type climbing robot for uneven vertical surfaces

Vertical wall surfaces with obstacles present a serious challenge for wall-climbing robots. Owing to their limitations in overcoming obstacles, these types of robots have not been commercialized yet. Several ideas on novel designs and precise control have been suggested; however, further research is required to achieve enhanced robot capabilities in overcoming obstacles. Specifically, the use of dry adhesive methods by wall-climbing robots to climb over obstacles present tremendous challenges. This study introduces the design of a new linkage-type, wall-climbing robot, based on dry adhesion, for uneven vertical surfaces. Based on a four-bar mechanism, repeated walking is achieved via a single actuator. The robot's most important feature is the linkage design used for climbing over obstacles, which has been adopted from rover running patterns. The symmetric linkage design renders the robot adaptable to uneven surfaces with a compliant motion. Additionally, flat dry adhesives were used for the attachment mechanism. The design parameters were determined based on kinematic and static analyses, and certain important issues in linkage-type wall-climbing robot designs were addressed. The robot's performance was verified using experiments, whereby it was able to climb up and go down stairs with maximum stair heights of 15 mm (equal to 0.6% of the robot's height) during open-loop vertical walking. We expect that the linkage design can extend the accessible area of the wall-climbing robot.This study introduces the design of a new linkage-type, wall-climbing robot, based on dry adhesion, for uneven vertical surfaces. Based on a four-bar mechanism, repeated walking is achieved via a single actuator. The robot's most important feature is the linkage design used for climbing over obstacles, which has been adopted from rover running patterns. The symmetric linkage design renders the robot adaptable to uneven surfaces with a compliant motion. Additionally, flat dry adhesives were used for the attachment mechanism. The design parameters were determined based on kinematic and static analyses, and certain important issues in linkage-type wall-climbing robot designs were addressed. The robot's performance was verified using experiments, whereby it was able to climb up and go down stairs with maximum stair heights of 15 mm (equal to 0.6% of the robot's height) during open-loop vertical walking. We expect that the linkage design can extend the accessible area of the wall-climbing robot.

Diversity and ecology of vascular plants established on the extant world-longest ancient city wall of Nanjing, China

Spontaneous vegetation established on the city wall constitutes a characteristic greenspace within the urban matrix. Nanjing city wall of the Ming Dynasty (NJCW), as an extraordinary huge defensive masonry project, was built in 1393, the extant, basically intact ancient city wall is 25.09km long, 9–26m high, and is protected now as a key national cultural relic. Species composition and life forms of the vascular plants established on the vertical or inclined wall surfaces of NJCW were investigated, and its diaspore sources and dispersal modes were also analyzed. Totally, 159 species in 125 genera of 70 families were found inhabiting the joints between bricks or between block stones, trees, shrubs and woody lianas accounts for 51.57% of the species assemblage, while herbaceous plant species makes up 48.43% of them. Fifteen alien species were found colonizing NJCW, including 12 invasive species. Six 100-m-long quadrats were sampled in different segments of NJCW, each quadrat contained 39–77 species, and 755–3006 individuals. In total, 10785 individuals of vascular plants were recorded, consisting of 104 species in 89 genera of 56 families. 65.25% of the total individuals, and 53.85% of the total species are adapted to the primary dispersal of diaspores by wind, whereas 34.75% of the individual assemblage, and 46.15% of the species assemblage are adapted to the primary dispersal of seeds by birds. A bird-dispersed, native pioneer tree, Broussonetia papyrifera, was the most abundant species among the six quadrats, even developed coppices on the vertical wall surface. Location and aspect of the quadrats may have affected the species diversity of vascular plants established on its wall surfaces. A diversity of vascular plants established on NJCW, as a valuable urban ecological heritage, is worthy of sustainable wall management, while management priorities should be given to those large trees inhabiting the walls made of bricks, and to the invasive alien species to prevent them from further spreading over the adjacent urban habitats.

INTEGRATING TERRESTRIAL LIDAR WITH POINT CLOUDS CREATED FROM UNMANNED AERIAL VEHICLE IMAGERY

Abstract. Using unmanned aerial vehicles (UAV) for the purposes of conducting high-accuracy aerial surveying has become a hot topic over the last year. One of the most promising means of conducting such a survey involves integrating a high-resolution non-metric digital camera with the UAV and using the principals of digital photogrammetry to produce high-density colorized point clouds. Through the use of stereo imagery, precise and accurate horizontal positioning information can be produced without the need for integration with any type of inertial navigation system (INS). Of course, some form of ground control is needed to achieve this result. Terrestrial LiDAR, either static or mobile, provides the solution. Points extracted from Terrestrial LiDAR can be used as control in the digital photogrammetry solution required by the UAV. In return, the UAV is an affordable solution for filling in the shadows and occlusions typically experienced by Terrestrial LiDAR. In this paper, the accuracies of points derived from a commercially available UAV solution will be examined and compared to the accuracies achievable by a commercially available LIDAR solution. It was found that the LiDAR system produced a point cloud that was twice as accurate as the point cloud produced by the UAV’s photogrammetric solution. Both solutions gave results within a few centimetres of the control field. In addition the about of planar dispersion on the vertical wall surfaces in the UAV point cloud was found to be multiple times greater than that from the horizontal ground based UAV points or the LiDAR data.

A Gecko-Inspired Electroadhesive Wall-Climbing Robot

Geckos can climb fast on vertical wall surfaces, whether dry or wet, smooth or rough. The principles of a gecko?s attachment abilities have been studied in detail, and wall-climbing robots based on the biomimetic adhesion of geckos have been proposed. However, the synthetic dry fibrillar adhesive that mimics the gecko?s adhesive footpad is still under development and does not yet achieve as high performances as a gecko. This adhesion method has some disadvantages, such as low payload and sensitivity to surface contaminants involving dust. Many studies have been conducted on the bionic design of robots to simulate a gecko?s motion but using other adhesive mechanisms instead. By combining the gecko?s motion modes and the specific adhesive mechanisms, various novel wall-climbing robots can be envisioned.

Thermal Impacts of Vertical Greenery Systems

Abstract - Using vertical greenery systems to reduce heat transmission is becoming more common in modern architecture. Vertical greenery systems are divided into two main categories; green facades and living walls. This study aims to examine the thermal performance of vertical greenery systems in hot and humid climates. An experimental procedure was used to measure indoor temperature and humidity. These parameters were also measured for the gap between the vertical greenery systems and wall surfaces. Three boxes were used as small-scale rooms. Two boxes were provided with either a living wall or a green facade and one box did not have any greenery (benchmark). Blue Trumpet Vine was used in the vertical greenery systems. The data were recorded over the course of three sunny days in April 2013. An analyses of the results showed that the living wall and green facade reduced indoor temperature up to 4.0 °C and 3.0 °C, respectively. The living wall and green facade also reduced cavity temperatures by 8.0 °C and 6.5 °C, respectively.

DEVELOPMENT OF cm-SCALE WALL CLIMBING HEXAPOD ROBOT WITH CLAWS

In this paper, we investigate the slip condition on a vertical wall surface and propose a cm-scale hexapod robot with claws that can climb the vertical wall. Since the volume force such as gravity is proportional to the length cubed and the area force such as muscle force is proportional to its cross section, i.e., the length squared, an object is more capable of overcoming gravity the smaller it is. This scaling effect allows a small robot to fly easily, accelerate rapidly, and climb a vertical wall with minimal difficulty. We developed a claw-type hexapod robot with a body length of 8.5cm and weight of 13.5g and realized horizontal and vertical movement on a vertical wall. In addition, we used a mathematical model and an experimental result to analyze the relationship between the gripping ability of the claws and the surface properties of the wall.

Thin film flow of magnetohydrodynamic (MHD) pseudo-plastic fluid on vertical wall

The effect of the transverse magnetic field on the thin film flow of pseudo-plastic fluid for lifting and drainage on a vertical (wall) surface is investigated. Approximate solutions are obtained analytically and numerically for the resulting non-linear and inhomogeneous ordinary differential equations arising from the constitutive equation of the pseudo-plastic fluid. Physical quantities such as the velocity profile, volume flux, average velocity, shear stress, vorticity and the force exerted by fluid on the belt surface respectively for lift and drainage are calculated. The condition for the net upward flow for lift case has also been investigated. The effect of different parameters such as the magnetic effect M2, the non-Newtonian parameter β, the Stokes number St on velocity profiles and shear stress are presented via graphs. The analysis for the analytical solution is carried out for small value of β. The analogy of the velocity profiles of MHD pseudo-plastic and MHD Newtonian fluids reveals that the MHD pseudo-plastic fluid drains down the upward moving belt faster than the MHD Newtonian fluid whereas in drainage, the behavior of the velocity profiles is vice versa. In other words, the applied magnetic field generally reduces the flow velocity in the lifting case, while, in the drainage case, the magnetic field and the velocity field are shown to have a direct relation.

Vertical Wall Formation and Material Flow Control for Incremental Sheet Forming by Revisiting Multistage Deformation Path Strategies

In this article, multistage deformation path strategies for single point incremental forming (SPIF) are revisited with the purpose of controlling material flow (improving sheet thickness distribution) and forming a vertical wall surface for cylindrical cups. It is noted that stretching and thinning are two main deformation modes during SPIF. How to control material flow in an optimal way is a key point for successful forming. Multistage incremental forming shows more advantages than single-stage forming, especially dealing with shapes with steep walls. In this study, three basic multistage deformation path strategies have been proposed, that is: A. incremental part diameter; B. incremental draw angle; and C. incremental part height and draw angle. Those strategies and their combinations have been evaluated in terms of formability and compared in order to understand the material allocation mechanism and optimize the multistage forming process. In addition, approximate plane-strain analysis models have been given to provide formability predictions between single-stage and multistage strategies, and between strategies B and C, respectively. The prediction results show good agreement with the experimental results. It is demonstrated that the strategic combination A + B is the optimal way to achieve the forming target.

Experiment for Attaching Force of a Suction Fan on Various Concrete Wall Surfaces

In order to measure attaching performance of the suction fan against a concrete wall, test apparatus measuring suction force of the fan was developed. Using this test apparatus, four types of concrete wall specimens were tested to measure the attaching force. The test apparatus consisted of a fan motor, a pneumatic cylinder, a load cell, and sensors for vacuum pressure and a rotating speed of the fan. Vertical wall surface of concrete material were manufactured to four different shapes that is flat, step, rib and embossing type. When the fan is rotating in the fan-housing which is fixed by metal frame, the wall specimen is moved near to fan-housing edge by the pneumatic cylinder. And the specimen may be attached to fan-housing edge by suction force of the fan, and the wall specimen is reversely moved away from the fan-housing edge by the pneumatic cylinder. Then suction force of the fan was measured using a load cell. And the suction force was measured depending on specimen types and varying the rotation speed of the fan. Test result shows that the fan speed is proportional to the suction force, and interestingly, suction force is almost independent from the specimen shapes. The maximum suction force was equally measured with 231.9 N on the step and embossing type surface with 1,800 rpm.

A study of surface roughness variation in ultrasonic vibration-assisted milling

The objective of this paper is to investigate the effects of assisted ultrasonic vibration on the surface roughness of machined surfaces in micro-end-milling. Series of slot-milling experiments were conducted with aluminum alloy as workpiece material. The surface roughness of slot bottom surface and vertical side wall surface of slot was studied, respectively. It is found that surface roughness of the machined slot bottom surface could increase to varying degrees because of ultrasonic vibration in most of the studied cases, and this deterioration becomes more apparent when large feed per tooth and low-spindle speed were adopted. As for the vertical side wall surface of the slot, there is an obvious improvement of surface roughness when ultrasonic vibration is applied. Based on analysis of variance analysis, further study indicates that the surface roughness of vertical side wall surface of the slot is determined by several key parameters including spindle speed, feed per tooth and amplitude in ultrasonic vibration-assisted milling. An optimal combination of these parameters is of great benefit to achieving small surface roughness.

Development and control of flexible pneumatic wall-climbing robot

A new kind of flexible pneumatic wall-climbing robot, named WALKMAN-I, was proposed. WALKMAN-I is basically composed of a flexible pneumatic actuator (FPA), a flexible pneumatic spherical joint and six suction cups. It has many characteristics of low-cost, lightweight, simple structure and good flexibility. Its operating principle was introduced. Then three basic locomotion modes, which are linear motion, curvilinear motion and crossing the orthogonal planes, were presented. The safety conditions of WALKMAN-I were discussed and built. Finally, the control system was designed and experiments were carried out. Experimental results show that WALKMAN-I is able to climb on the vertical wall surface along a straight line or a curved path, and has the ability of crossing orthogonal planes and obstacles. The maximum rotation angle reaches 90°, the maximum velocity reaches 5 mm/s, and the rotation angle and the moving velocity of WALKMAN-I can be easily controlled.

A method of evaluating heat transfer during nonisothermal absorption

A method of carrying out an engineering calculation of heat and mass transfer during nonisothermal absorption on a solution film that flows down a vertical wall surface is proposed.