Freeway ramp metering based on PSO-PID control

Ramp metering on freeway is one of the effective methods to alleviate traffic congestion. This paper advances the field of freeway ramp metering by introducing an application to the on-ramp, capitalizing on the macro traffic follow theory and improved the freeway traffic flow. The Particle Swarm Optimization (PSO) based on Proportional Integral Derivative (PID) controller is further developed to single ramp metering as well as to optimize the PID parameters. The approach is applied to a case study of the Changyi Freeway(G5513) in Hunan, China. The simulation is conducted by applying the actual profile traffic data to PID controller to adjust the entering traffic flow on the freeway on-ramp. The results show that the PSO-PID controller tends to converge in about 80 minutes, and the density tends to be stable after 240 iterations. The system has smaller oscillation, more accurate adjustment of ramp regulation rate, and more ideal expected traffic flow density. The traffic congestion on mainline is effectively slowed down, traffic efficiency is improved, and travel time and cost are reduced. The nonlinear processing ability of PSO-PID controller overcomes the defects of the traditional manual closing ramp, and can be successfully applied in the field of intelligent ramp metering.

Design of On-line Detecting Device for Groove Wear of Elevator Traction Wheel

After the wear of elevator traction wheel, there is a traditional detection method which can measure the geometric dimensions of wheel groove. But this method has low measurement accuracy and cannot accurately reflect the actual profile of wheel groove. By means of the machine vision inspection technology, the profile of the traction wheel groove can be measured, a new detection method is proposed in this paper, and the corresponding measuring device is designed in detail. At the same time, with help of the computer simulation, the processing of the work piece image is used. In this method, the size and profile of the wheel groove of the traction wheel can be measured more accurately and quickly to reflect the actual wear value of the wheel groove.

Key competencies of traders in municipal markets: case study in the Livramento Market of Setubal

Purpose – This study aims to analyse the role and importance of trader’s competencies in the context of municipal markets. It is proposed to define the ideal competences profile of traders (ICPT) in a municipal market – Livramento Market of Setubal, Portugal – attending to their key competencies, to assess the degree of similarity between the actual profile of the traders and the ICPT.Design/methodology/approach – A case study was carried out with a quantitative approach through the application of a survey to individuals of the various stakeholders’ groups (N = 36) related to the municipal markets.Findings – The ordering the relative importance of the competencies allowed to obtain the ICPT, highlighting the greater importance of more technical competencies in detrimental of soft competencies. Each of the competence’s profiles identified by the different groups were compared to the ICPT and high percentages of similarity were obtained (greater than 70%).Research implications – This study assists professional associations and managers in the design of local market management models with a focus on competencies, guiding their efforts towards the development of the most relevant competencies for professional practice.Originality/value – Its originality is based on the lack of research studies focused on the analysis of the competences of the players in the municipal markets. The analysis of the central role of a profession that is little valued, and little studied in the national context serves as an anchor for other studies on the competencies of these professionals.

Model updating of a temperature field simulation of a printed circuit board assembly based on the Kriging model

Purpose The simulated temperature profile of the printed circuit board assembly (PCBA) during reflow soldering process deviates from the actual profile. To reduce this relative deviation, a new strategy based on the Kriging response surface and the Multi-Objective Genetic Algorithm (MOGA) optimizing method is proposed. Design/methodology/approach The simulated temperature profile of the PCBA during reflow soldering process deviates from the actual profile. To reduce this relative deviation, a new strategy based on the Kriging response surface and the MOGA optimizing method is proposed. Findings Several critical influencing parameters such as temperature and the convective heat transfer coefficient of the specific temperature zones are selected as the correction parameters. The hyper Latins sampling method is implemented to distribute the design points, and the Kriging response surface model of the soldering process is constructed. The updated model is achieved and validated by the test. The relative derivation is reduced from the initial value of 43.4%–11.8% in terms of the time above the liquidus line. Originality/value A new strategy based on the Kriging response surface and the MOGA optimizing method is proposed.

Kinematic calculation and plotting of lifting height and speed of the tangential cam pusher using MATHCAD program

The article shows the design features of tangential cams with a rounded top, provides a method for determining the lifting height and speed of the pusher when the roller is rolling in a straight line and in contact with the actual profile of the cam. The formulas for the kinematic calculation of the tangential cam are refined taking into account the radius of the initial circumference of the shaft, the radius of the rounding of the cam tip and the value of the radius of the pusher roller. Calculations are given to determine the stroke and speed of the pusher when the roller is rolling on the sections of the straight and arc-shaped surface of tangential cams with a radius of rounding of 6 and 10 mm. Formulas are proposed for determining the lift of the pusher in the rolling section of the roller along the radius of the cam tip at a constant coefficient λ = 1 and λ = 1,5. Using the Mathcad program calculations are performed and combined graphs of the pusher lift and the change in its speed are constructed for two types of tangential cams

Build Orientation Effect on Geometric Performance of Curved-Surface 316L Stainless Steel Parts Fabricated by Selective Laser Melting

Selective laser melting (SLM) is a powder bed fusion additive manufacturing technology that allows the production of high-performance metal parts with geometrically complex shapes, such as curved surface, can be used in practical engineering applications. In recent years, systematic attempts have been made to uncover the material-process-microstructure-property linkage in SLM-fabricated planar-surface metal parts; however, little is known on the performance and quality of SLM-fabricated metal parts with curved surfaces. In this paper, we studied the effects of build orientation on the geometric performance of SLM-built 316L stainless steel (SS) samples with a sinusoidal curved surface. The results indicated that the average values of profile roughness Ra and surface texture attributes Sa, Sk, and Vmc decreased with the increase in build orientation. Moreover, the locations at curvatures C2 and C4 exhibited the best surface finish at the build orientation of 75 deg and 90 deg. In addition, the least square method was used to fit the actual profile of the curved surface of as-built samples fabricated at each build orientation, and it was found the actual profile demonstrated the best consistency with the designed one at 90 deg build orientation. In this paper, the process–curvature–geometric performance relationship of SLM-built metal parts with curved surface was uncovered. In addition, this paper provides keen insights into assessing the geometric performance of SLM-built curved-surface metal parts and establishes a roadmap toward SLM-fabrication of metal parts with complex geometries for practical engineering applications.

Analysis of the velocity distribution in different types of ventilation system ducts

The paper presents the results obtained during the preliminary studies of circular and rectangular ducts before testing the properties elements (elbows, tees, etc.)of rectangular with rounded corners ducts. The fundamental problem of the studies was to determine the flow rate in the ventilation duct. Due to the size of the channel it was decided to determine the flow rate based on the integration of flow velocity over the considered cross-section. This method requires knowledge of the velocity distribution in the cross section. Approximation of the measured actual profile by the classic and modified Prandtl power-law velocity profile was analysed.