Analysis of international EPC projects using SCOR model, MoneteCarlito simulation, and relationship management

The EPC contracting mode (Engineering, Procurement and Construction) has been broadly applied in construction projects, particularly, at the international level. However, the procurement process has been scarcely in literature. The purpose of this thesis is to research the procurement processes of different types of products—ETO (Engineer to order), MTO (Make to order), and MTS (make to stock)—in supply chain for a real international EPC cement project in Ethiopia. The procurement processes of steel bar (MTS), precast steel structure (MTO), and vertical mill (ETO) for the “Raw Meal Grinding and Exhaust Gas Treat,” one of the cement plant workshops, have been analyzed as a case study. Three levels’ of SCOR models (Supply Chain Operation References) for the three products are established; the inventory costs were selected as the performance measure for the supply chain. The SCOR models helped in finding the locations where the inventory costs were incurred, and helped in identifying the factors that may influence the inventory cost. In addition, based on the SCOR models, a basic simulation model has been set up, MonteCarlito simulation, and was applied to the precast steel structure based on the inventory cost. A sensitivity analysis was conducted to evaluate the impacts of the pre-delivery waiting time, the delivery time, and the construction time on the total inventory cost. The results revealed that the construction time has the highest impact. Moreover, high inventory cost resulted from poor management relationship with the import agent company. Four key elements were identified which leading to such a relationship: trust, collaboration communication, and problem solving. A questionnaire about these four key elements was developed and responses analyzed (38 responses). Ten suggestions were made to improve the relationship management with suppliers

Dynamic characteristics of joint surface considering friction and vibration factors based on fractal theory

From the point of view of the micro-geometry, most joint surfaces are composed of the rough surfaces with the self-affine fractal characteristics. And the fractal characteristics have a large impact on the dynamic behaviors of the composite structures notably. In this paper the dynamic characteristics of the joint surface are discussed with the friction and vibration coupling effect considered based on fractal theory. Friction and vibration are caused by the rough surfaces. Firstly the expressions of the stiffness and damping model are obtained based on the fractal contact theory. Secondly the contact parameters of the joint surfaces are studied and analyzed with the contact surfaces replaced by the equivalent damping layer with the stiffness and damping model. Thirdly, based on the fractal contact theory, the contact pairs are established by ANSYS to simulate the effect of the characteristics of joint surfaces by the finite element method. Finally the natural frequency and model analysis obtained from theory and experiment of the composite beams are comparatively analyzed. The results show that the established stiffness and damping models are well suitable for the reality of the joint surface

Dynamics of mass-spring-belt friction self-excited vibration system

In order to deeply study the non-smooth dynamic mechanism of self-excited vibration, the friction self-excited vibration system model containing the Stribeck friction model is established, which is a nonlinear dynamical mass-spring-belt model. For the established model, the critical instability speed is solved by the first approximate stability criterion of Lyapunov theory, and the stability of limit cycle is determined on the basis of curvature coefficient. Secondly, the bifurcation characteristics and system behaviors under different parameters are analyzed by using numerical simulation method. The results show that the theoretical analysis is feasible. Feed speed, damping coefficient and ratio of dynamic-static friction coefficient are the main factors that affect the system motion state. Thirdly, the Washout filter method is designed to control the bifurcation characteristics. By comparing the pre and post phase diagrams, results show that the amplitude of controlled system is reduced and the topology is improved after introducing the Washout filter. All the researches above prove that adding Washout filter into the system to control the bifurcation phenomenon is a more effective method

Longitudinal control for person-following robots

Purpose: This paper aims to address the longitudinal control problem for person-following robots (PFRs) for the implementation of this technology. Design/methodology/approach: Nine representative car-following models are analyzed from PFRs application and the linear model and optimal velocity model/full velocity difference model are qualified and selected in the PFR control. Findings: A lab PFR with the bar-laser-perception device is developed and tested in the field, and the results indicate that the proposed models perform well in normal person-following scenarios. Originality/value: This study fills a gap in the research on PRFs longitudinal control and provides a useful and practical reference on PFRs longitudinal control for the related research

A Quantization-Friendly Separable Convolution for MobileNets

As deep learning (DL) is being rapidly pushed to edge computing, researchers invented various ways to make inference computation more efficient on mobile/IoT devices, such as network pruning, parameter compression, and etc. Quantization, as one of the key approaches, can effectively offload GPU, and make it possible to deploy DL on fixed-point pipeline. Unfortunately, not all existing networks design are friendly to quantization. For example, the popular lightweight MobileNetV1, while it successfully reduces parameter size and computation latency with separable convolution, our experiment shows its quantized models have large accuracy gap against its float point models. To resolve this, we analyzed the root cause of quantization loss and proposed a quantization-friendly separable convolution architecture. By evaluating the image classification task on ImageNet2012 dataset, our modified MobileNetV1 model can archive 8-bit inference top-1 accuracy in 68.03%, almost closed the gap to the float pipeline.Comment: Accepted At THE 1ST WORKSHOP ON ENERGY EFFICIENT MACHINE LEARNING AND COGNITIVE COMPUTING FOR EMBEDDED APPLICATIONS (EMC^2 2018