Evaluation of Collaborative Robot Sustainable Integration in Manufacturing Assembly by Using Process Time Savings

Collaborative robots are enablers of flexibility in the current dynamic and uncertain manufacturing environment. Decision making on its implementation requires technical feasibility, involving productivity and workforce implications that should be faced in an integrated perspective in processes where many components of different materials are assembled in products of increasing diversity and complexity. This study introduces two new parametric models for collaborative robotics, formulated in order to evaluate the differential cost of assembly (economic dimension) and the differential income from taxes that supports short-term workforce displacement (social dimension) in cobot implementation. Updated techno-economical parameters are selected for assessing feasibility ranges of application in different production scenarios. Next, the influence curves of productivity gain for a feasible implementation of cobot establish thresholds for decision making under both criteria. The results show the need for productivity gains that are significantly lower in high-wage scenarios than in low-wage scenarios; however, in a joint approach, breakeven productivity gain is always higher for the social dimension threshold than for the economic requirement of cost-effective manufacturing, with a higher gap in low-wage cases. The detailed analysis of a real case study of cobot implementation for assembly demonstrates the practical application of models and potential for future research.

Study on the Measurement Method of the Crack Local Flexibility of the Beam Structure

The crack which appears in the structure can be described by a local flexibility. With the occurrence and propagation of crack, the local flexibility will change. The change can effectively reflect the damage degree of the structure. In this paper, the measurement method of the crack local flexibility of the beam structure is presented. Firstly, a series of sample points are selected at the crack location and the possible value range of the crack local flexibility, and then these sample points are used as input parameters for the dynamic analysis of the beam structure. The vibration equation of beam structure is solved, and the frequency influence surface is drawn. In addition, the vibration signal of the beam is tested, and the first three order natural frequencies can be obtained. Thirdly, these frequencies measured are adopted to cut the natural frequency influence surfaces, and then the first three order natural frequency influence curves are drawn. The intersection points of these frequencies influence curves can indicate the crack local flexibility and the corresponding crack location. This method is suitable for measuring the local flexibility of crack with different shapes and types in the beam structure which have various cross sections.

Complex Contagions in Charitable Donations

Cascades over social networks can spread information, beliefs, diseases, technologies, and behaviors. Simple cascades spread from mere contact and produce submodular influence curves. Complex cascades assume agents with thresholding behavior and may produce non-submodular influence curves. In this study, we run three experiments that request charitable donations from human participants and experimentally manipulate whether and where their peers donate. We find evidence that we can (1) direct donations to an otherwise unpopular charity and (2) elicit complex contagion as evidenced by a non-submodular influence curve. The findings represent the most straightforward evidence to date of treatment-induced complex contagion - explicitly and formally defined - in human decision-making.

Longitudinal Mediation Analysis with Time-varying Mediators and Exposures, with Application to Survival Outcomes

Abstract:1 In this paper, we study the effect of a time-varying exposure mediated by a time-varying intermediate variable. We consider general longitudinal settings, including survival outcomes. At a given time point, the exposure and mediator of interest are influenced by past covariates, mediators and exposures, and affect future covariates, mediators and exposures. Right censoring, if present, occurs in response to past history. To address the challenges in mediation analysis that are unique to these settings, we propose a formulation in terms of random interventions based on conditional distributions for the mediator. This formulation, in particular, allows for well-defined natural direct and indirect effects in the survival setting, and natural decomposition of the standard total effect. Upon establishing identifiability and the corresponding statistical estimands, we derive the efficient influence curves and establish their robustness properties. Applying Targeted Maximum Likelihood Estimation, we use these efficient influence curves to construct multiply robust and efficient estimators. We also present an inverse probability weighted estimator and a nested non-targeted substitution estimator for these parameters.

Efficiency Analysis of Low-Grade Energy Recovery System Based on Scroll Expander

A new energy recovery system based on scroll expander is presented according to the characteristics of low-grade energy in this paper. It is discussed for the expression of the system efficiency and its influential factors with the method of Exergy Analysis. And the influence curves of relationship between the expander’s inlet pressure and system efficiency are obtained through computer simulation and laboratory experiments. The test result of the comparison of different the recycling system shows that the recycling method based on scroll expander is more efficiently than others in the area of recycling low-grade energy.

Dynamic Analysis and Structural Optimization for a Logging while Drilling Neutron Instrument

Logging while drilling (LWD) neutron instrument is a core equipment of the pulsed neutron logging technology, its anti-vibration performance has a direct impact on the measurement accuracy. For improving the anti-vibration performance, a reverse design method was proposed to avoid the resonance region due to increasing structural stiffness. The dynamic performance of the original instrument was analyzed, the weaknesses of its anti-vibration performance were determined and its topologies were improved. Moreover, the structural parameters of the instrument were optimized to raise the structural base frequency. The results show that the base frequency of the instrument increases high enough, the influence curves and surfaces of the base frequency with design variables provide a theoretical reference for the design of a LWD neutron instrument.

The Monitoring and Numerical Simulation Analysis on the Construction of a Shallow Underpass

Based on the dynamic monitoring project of one underpass in Dalian, this paper tries to validate the control effect of the ground settlement on the stability of tunnel surrounding rocks during construction of underground passage under urban arterial road by means of analyzing the vertical ground settlement curves, convergence curves of tunnel inner perimeter and vault displacement curves. With the numerical calculation tool of the software FLAC, it also analyzes the construction of XS-2 # cross-section which was in the south side of the whole construction section at different stages by adopting the plane-strain model. Therefore, we can get the influence curves of ground settlement under different construction stages with considering the release of stress. The simulation results are basically consistent with the measured data, which has a great significance for the subsequent design and construction of underground projects with similar geological conditions.

Load Bearing and Mass Relation Contrast between Composite Shell and Alloy Shell

To improve work efficiency of cabin and solve the contradiction between load bearing and mass, combining parametric modeling and optimization theory,the influence curves of load bearing on mass are proposed. Applying stress state theory, combining distortion energy theory criterion and Tsai-Wu failure criterion, shells load bearing is theoretically analysed. Contrast results are, in the same load condition, compared with alloy, the weight of composite reduces 46.2%;in the same weight condition, the load bearing of composite increases 75%. At present, the cabin load bearing is 0.04MPa, to improve work efficiency, increasing to 0.055MPa and replacing alloy by composite, the load bearing increases 37.5%, while the weight reduces 26.1%, then the contradiction between work efficiency and mass is coordinated.

The Analytical Solution of Single Pipe Piles under Axially and Laterally Free Loads

The analytical solution of a single pipe piles under axially and laterally loads is presented, when the laterally loads is optional free load. As piles foundations are becoming a preferred foundation type, piles usually work under simultaneous axial and lateral loads in engineering. To analyze the function of free loads to pipe piles under inclined loads conditions, in the basis of ‘m’ method, deformation differential equation of elastic piles under inclined loads is established first in the paper with analytical method. Differential equation has two parts in according to the piles in the earth or in the air, and lateral deformation, obliquity, moment; shearing force of the piles can be gotten respectively by soluting equations. In the end of the paper, influences of several parameters is analyzed of the top axial loads, the top lateral loads and the free loads, and their influence curves are given.

Critical Force Analysis of a Cantilever Column Subjected to a Subtangential Follower Force and a Vertical Force

The stability of a cantilever column subjected to a subtangential follower force and a vertical force is discussed for investigating the effects of these factors on the critical force. The governing differential equation of the system and the corresponding boundary conditions are established, and the exact solution is found out by integrating the differential equation. Based on the exact solution, the effects of the parameters relating to the subtangential follower force and the vertical force on the critical force are analyzed, and discussions for these results are performed， the influence curves of the subtangential follower force parameter and the vertical force parameter to the critical force are plotted. The results show that the parameter of a subtangential follower force can be bigger than 1/2, even equal to 1.0, with taking into account of the effect of the vertical force.