China
Africa
Explore chapters and articles related to this topic
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
When acquiring aerial photogrammetry for topographic mapping and other purposes, control points must be established within a coordinate system consistent with other mapped features. Linking the aerial photography to the monumentation network is achieved by referencing the aerial photographs to known points on the ground that can be clearly identified in the photographs. This is typically done by painting, that is, laying down of panels (or in many cases, taping) white or contrasting colored marks on the ground in the shape of an “ X ” or a “ V ” that can be clearly identified in the photograph. These marks are then tied to the monument system conventionally with ground surveys. The end result is an aerial photograph, or series of photographs, rectified to accurately illustrate the existing topography on the proper coordinate system. Once the aerial photographs are produced, they are digitized into graphic elements that are directly incorporated into a GIS. With the horizontal position of the topographic features, the elevation contours and many specific point elevations can be determined as well.
Distributionally robust and risk-averse optimisation for the stochastic multi-product disassembly line balancing problem with workforce assignment
Published in International Journal of Production Research, 2022
Xin Liu, Feng Chu, Feifeng Zheng, Chengbin Chu, Ming Liu
In this work, the workload balance between opened workstations is regulated via the CVaR constraints combining with the minimisation of the opened workstation number. However, the widely used criterion of optimising balance measures, such as minimising the total idle times and minimising the maximal workload difference between opened workstations, may have more advantages in balancing workstations' workloads (Kalayci and Gupta 2014; McGovern and Gupta 2015). Besides, workers' preference on their assigned tasks is not considered in this work, which may lead to the reduction of the fairness of employees. In addition, during the disassembly process, directions of the EOL product while removing different components may be different. For example, an EOL refrigerator may be laid down from vertical position to the horizontal position. Direction changes may be required between two consecutive tasks, leading to a higher cost. Therefore, our future research directions may include: (1) investigating the bi-objective optimisation program, to minimise the total cost and the total idle times simultaneously; (2) studying the problem where workers' dissatisfaction is included in the objective; (3) incorporating the direction changes between consecutive tasks into objective function.
Effect of loading rates on the behaviour of epoxy-repaired RC beam–column connections
Published in European Journal of Environmental and Civil Engineering, 2018
Comingstarful Marthong, Sajal K. Deb, Anjan Dutta
Typical schematic diagram of the test set-up as shown in Figure 3 was used for experimental investigation. Application of load was facilitated by strong floor, strong wall and A-frames available in the Dynamic Structural Testing Facility at IIT Guwahati. Servo hydraulic dynamic actuators (Make: MTS, USA) of capacity 250 kN having a maximum displacement range of ±125 mm was used. The column of the connection was placed in horizontal position, while the beam was placed in vertical position in the set-up. An axial load of 10% gross capacity of column was applied to the column to represent gravity load as recommended by Ghobarah, Aziz, and Biddah (1997). The load on the column was applied by a 500 kN capacity jack. The jack was abutting against an A-frame which was fabricated for the specified load carrying capacity. To simulate the support condition at both ends of the column, roller supports were fabricated by making grooves inside mild steel plates. The actual testing arrangement of specimens is shown in Figure 4. The MTS actuator was equipped with internal load cell and linear variable differential transformer for measuring actuator force and displacement, respectively.
Influence of aggregate morphology on the mechanical performance of asphalt mixtures
Published in Road Materials and Pavement Design, 2018
Daniel Castillo, Silvia Caro, Masoud Darabi, Eyad Masad
After the aggregate particles are created, they are computationally “graded”, that is, their sizes are adjusted to follow a predefined gradation. To accomplish this, the shortest diameter of each particle is rotated to the vertical position, so that the aggregate is located in a horizontal position. The height of the particle, or vertical distance between the maximum and minimum y-coordinates of the polygon, is defined as the “sieve” size of the aggregate (Figure 2(a)). Then, the x- and y-coordinates of the aggregates are multiplied by a factor such that the sieve sizes of the aggregate sample comply with the specified gradation. In a later stage (see Section 3.2) aggregates are rotated to their final position within the virtual HMA samples. An example of a set of 100 coarse aggregates complying with the gradation presented in Table 1 is presented in Figure 2(b).