Search results

Polishing is a crucial process in mechanical manufacturing. The use of industrial robots to automate polishing is an inevitable trend in future developments. However, current robotic polishing tools are too large to reach inside deep holes or grooves in workpieces. This study aims to use a pneumatic artificial muscle (PAM) as the actuator and designs a force-controlled end-effector to reach inside the deep and narrow areas in the workpiece.

This approach first addresses the challenge of converting the tensile force generated by the PAM into pushing force through mechanism design. In addition, a dynamics model of the end-effector was established based on the three-element model of the PAM. A combined control strategy was proposed to enhance force control accuracy and adaptability during the polishing process.

Experiments were conducted on a robotic platform equipped with the proposed end-effector. The experimental results demonstrate that the end-effector can polish the inner end face of holes or grooves with diameters as small as 80 mm and depths reaching 200 mm. By implementing the combined control strategies, the target force tracking error was reduced by 48.66% compared to the use of the PID controller alone.

A new force-controlled end-effector based on the PAM is designed for robotic polishing. According to the experimental result, this end-effector can polish not only the outer surfaces of the workpiece but also the internal surfaces of workpieces with deep holes or grooves specifically. By using the combined control strategy proposed in this paper, the end-effector significantly improves force control precision and polishing quality.

Imitation learning is a powerful tool for planning the trajectory of robotic end-effectors in Cartesian space. Present methods can adapt the trajectory to the obstacle; however, the solutions may not always satisfy users, whereas it is hard for a nonexpert user to teach the robot to avoid obstacles in time as he/she wishes through demonstrations. This paper aims to address the above problem by proposing an approach that combines human supervision with the kernelized movement primitives (KMP) model.

This approach first extracts the reference database used to train KMP from demonstrations by using Gaussian mixture model and Gaussian mixture regression. Subsequently, KMP is used to modulate the trajectory of robotic end-effectors in real time based on feedback from its interaction with humans to avoid obstacles, which benefits from a novel reference database update strategy. The user can test different obstacle avoidance trajectories in the current task until a satisfactory solution is found.

Experiments performed with the KUKA cobot for obstacle avoidance show that this approach can adapt the trajectories of the robotic end-effector to the user’s wishes in real time, including trajectories that the robot has already passed and has not yet passed. Simulation comparisons also show that it exhibits better performance than KMP with the original reference database update strategy.

An interactive learning approach based on KMP is proposed and verified, which not only enables users to plan the trajectory of robotic end-effectors for obstacle avoidance more conveniently and efficiently but also provides an effective idea for accomplishing interactive learning tasks under constraints.

The purpose of this paper is to review, evaluate and classify the academic research that has been published in facility layout problems (FLPs) and to analyse how researches and practices on FLPs are.

The review is based on 166 papers published from 1953 to 2021 in international peer-reviewed journals. The literature review on FLPs is presented under broader headings of discrete space and continuous space FLPs. The important formulations of FLPs under static and dynamic environments represented in the discrete and continuous space are presented. The articles reported in the literature on various representations of facilities for the continuous space Unequal Area Facility Layout Problems (UA-FLPs) are summarized. Discussed and commented on adaptive and robust approaches for dynamic environment FLPs. Highlighted the application of meta-heuristic solution methods for FLPs of a larger size.

It is found that most of the earlier research adopted the discrete space for the formulation of FLPs. This type of space representation for FLPs mostly assumes an equal area for all facilities. UA-FLPs represented in discrete space yield irregular shape facilities. It is also observed that the recent works consider the UA-FLPs in continuous space. The solution of continuous space UA-FLPs is more accurate and realistic. Some of the recent works on UA-FLPs consider the flexible bay structure (FBS) due to its advantages over the other representations. FBS helps the proper design of aisle structure in the detailed layout plan. Further, the recent articles reported in the literature consider the dynamic environment for both equal and unequal area FLPs to cope with the changing market environment. It is also found that FLPs are Non-deterministic Polynomial-complete problems, and hence, they set the challenges to researchers to develop efficient meta-heuristic methods to solve the bigger size FLPs in a reasonable time.

Due to the extremely large number of papers on FLPs, a few papers may have inadvertently been missed. The facility layout design research domain is extremely vast which covers other areas such as cellular layouts, pick and drop points and aisle structure design. This research review on FLPs did not consider the papers published on cellular layouts, pick and drop points and aisle structure design. Despite the possibility of not being all-inclusive, the authors firmly believe that most of the papers published on FLPs are covered and the general picture presented on various approaches and parameters of FLPs in this paper are precise and trustworthy.

To the best of the authors’ knowledge, this paper reviews and classifies the literature on FLPs for the first time under the broader headings of discrete space and continuous space representations. Many important formulations of FLPs under static and dynamic environments represented in the discrete and continuous space are presented. This paper also provides the observations from the literature review and identifies the prospective future directions.

Nowadays, global warming, due to large-scale emissions of greenhouse gasses, is among top environmental issues. The purpose of this paper is to present a problem involving the incorporation of environmental aspects into logistics, which provides a comparison between pollution reduction and distance-based approaches.

In green vehicle routing problem (VRP), the aim is to model and solve an optimization problem in order to minimize the fuel consumption which results in reducing energy consumption as well as air pollution. The Gravitational Search Algorithm (GSA) is adapted and used as a powerful heuristic.

Here, it is shown that a set of routes with minimum length is not an optimal solution for FCVRP model since the total distance is not the only effective factor for fuel consumption and vehicle's load plays an important role too. In many cases, a considerable reduction in emissions can be achieved by only an insignificant increase in costs.

Green transportation is a policy toward reducing carbon emissions. This research focussed on routes problem and introduce FCVRP model. GSA is used as a powerful heuristic to obtain high quality routes in a reasonable time. Considering other factors that affecting fuel consumption could make this study more realistic.

When a distribution center receives all the information it needs about the demand from all the retail stores it supplies, a VRP is produced. So the models are valid for use by all goods producers and distributors. The preliminary assessment of the proposed model and method carried out on benchmark problems up to 200 nodes.

Fuel consumption is one of the most influential factors in transportation costs. This paper introduces an innovative decision-making framework to obtain optimum routes in a vehicle routes problem considering air pollution. The results were compared from fuel consumption as well as total travel distance viewpoints.

The aim of this study is to assess the mediating effect of source appearance (SA) and self-influencer congruence (SIC) on the relationship between visual content (VC) and customer engagement (CE) towards mobile advertisement.

This study uses a quantitative approach to test the proposed model based on the stimulus–organism–response (SOR) theory. The non-probability purposive sampling technique was used to collect data from Pakistani mobile users through a self-administered questionnaire.

The study results prove that VC alone cannot generate mobile users’ engagement. SA is the key in this regard, which has a relatively higher importance compared to SIC. Furthermore, the serial mediation effect of SA and SIC on CE shows that attractive sources are likely to induce higher SIC and subsequent CE.

The results reveal that without a pleasing SA and positive SIC, mobile users skip the ads by perceiving them to be irritating or interruptive. Mobile ads might cost relatively less, but the advertisers should understand the significance of the SA toward minimizing the mobile advertising skepticism.

Advertisers can enhance the user’s engagement on mobile devices by addressing both the SA and SIC in their VC. The combined effect of both the SA and SIC on CE has not been assessed before. Furthermore, this study has used the SOR mechanism to examine CE.

El objetivo general de esta investigación es evaluar el efecto mediador de la apariencia de la fuente (SA) y la congruencia del auto-influencer (SIC) en la relación entre el contenido visual (CV) y el compromiso del cliente (CE) hacia la publicidad móvil.

Este estudio utiliza un enfoque cuantitativo para probar el modelo propuesto basado en la teoría estímulo-organismo-respuesta (SOR). Se utilizó la técnica de muestreo intencional no probabilístico para recoger datos de usuarios de móviles paquistaníes mediante un cuestionario autoadministrado.

Nuestros resultados demuestran que el contenido visual por sí solo no puede generar el compromiso de los usuarios de móviles. La apariencia de la fuente es la clave a este respecto, que tiene una importancia relativamente mayor en comparación con la congruencia del auto-influencer. Además, el efecto de mediación en serie de SA y SIC en CE muestra que es probable que las fuentes atractivas induzcan un mayor SIC y el consiguiente compromiso del cliente.

Los resultados revelan que sin una SA agradable y una SIC positiva, los usuarios de móviles omiten los anuncios al percibirlos como irritantes o interruptores. Los anuncios para móviles pueden costar relativamente menos, pero los anunciantes deben comprender la importancia de la apariencia de la fuente para minimizar el escepticismo de la publicidad móvil.

Los anunciantes pueden mejorar la participación del usuario en los dispositivos móviles abordando tanto la AS como el SIC en sus contenidos visuales. Hasta ahora no se había evaluado el efecto combinado de la AS y el SIC en el CE. Además, este estudio ha utilizado el mecanismo del SOR para examinar el engagement del cliente.

本研究的总体目标是评估源外观（SA）和自我影响者一致性（SIC）对移动广告视觉内容（VC）和客户参与（CE）之间关系的中介效应。

本研究采用定量方法来检验基于刺激-有机体-反应（SOR）理论提出的模型。研究采用了非概率目的性抽样技术, 通过自填问卷的方式向巴基斯坦移动用户收集数据。

我们的研究结果证明, 仅靠视觉内容并不能引起移动用户的参与。在这方面, 源外观是关键, 与自我影响者一致性相比, 源外观的重要性相对更高。此外, SA 和 SIC 对 CE 的串联中介效应表明, 有吸引力的信息源可能会诱发更高的 SIC 和随后的客户参与。

研究结果表明, 如果没有令人愉悦的SA和积极的SIC, 移动用户就会认为广告具有刺激性或干扰性, 从而跳过广告。移动广告的成本可能相对较低, 但广告商应了解广告源外观对减少移动广告怀疑的重要性。

广告商可以通过在视觉内容中同时考虑广告联盟和广告投放中心这两个因素, 提高用户在移动设备上的参与度。之前从未有人评估过 “SA “和 “SIC “对消费者参与度的综合影响。此外, 本研究还使用了 SOR 机制来考察客户参与度。

The purpose of this paper is to explore external, mediator and moderator factors that influence tourist intention to use GPS-based navigation apps from the perspective of spatiotemporal tourist behavior (STTB).

A total of 636 valid questionnaires were selected from tourists visiting Lijiang Ancient Town. The partial least squares-structural equation modeling with the SmartPLS approach was adopted to estimate and validate the model.

The results of this paper showed that wayfinding efficiency, sensation-seeking behavior and spatial ability (SA) influence tourists’ intention to use (IU) navigation apps. A mediator of perceived location accuracy between SA and IU has been found. A multigroup generation moderator is verified in the model.

This paper provides a better understanding of the relationship between tourist spatiotemporal behavior and navigation apps, presenting practical suggestions for app developers, destination managers and vacation planners.

While the effects of information technology on tourist behavior have become a topic of interest among tourism industry stakeholders, this paper examines the effects of STTB on the acceptance of navigation apps in reverse, which enriches the theoretical framework.

本文从时空旅游行为 (STTB) 的角度探讨了影响游客使用基于 GPS 的导航应用程序的外部、中介和调节因素。

本研究共从丽江古城旅游者中抽取了636份有效问卷。采用 SmartPLS 方法的偏最小二乘结构方程建模 (PLS-SEM) 来估计和验证模型。

研究结果表明, 寻路效率 (WE)、感觉寻求行为 (SSB) 和空间能力 (SA) 会影响游客的使用意向 (IU) 导航应用程序。研究还发现感知位置准确度 (PLA)是空间能力 (SA) 和使用意图 (IU) 之间的中介变量。世代在多组比较模型中作为调节变量。

本文提供了对旅游时空行为与导航应用程序之间关系的更好理解, 为应用程序开发人员、目的地管理者和度假规划者提供了实用建议。

虽然信息技术对游客行为的影响已成为旅游业利益相关者感兴趣的话题, 但本文研究了 STTB 对导航应用程序接受度的影响, 从而丰富了理论框架。

This study elucidates the interactive relationship of sustainability assurance (SA) quality with corporate environmental sustainability performance (CESP) and firm value and explores the moderating impact of CESP on the SA quality–firm value relationship.

The sample comprises 320 firm-year observations of 40 companies listed on the Cotation Assistée en Continu (CAC 40) from 2010 to 2019. The authors use the simultaneous equations model to capture the CESP and SA quality–firm value relationship and apply the three-stage regression and generalised method of moments approaches to address possible endogeneity.

The results show that CESP, as assessed by International Organisation for Standardisation (ISO) 14001 certification, has a significant positive effect on firm value, the relevance of which implies that in the case of good environmental performance, society's perception of a firm is much more favourable; consequently, the firm is likely to be rewarded with a premium value in capital markets. In addition, environmental performance has a stronger interaction with SA quality, acting as a moderator variable; thus, greater SA quality signals credibility owing to increased eco-efficiency. The authors interpret their findings within a multi-theoretical framework that draws insights from legitimacy, stakeholders and signalling theoretical perspectives.

This study contributes to the literature by re-examining the relationship between SA quality and firm value. It also provides new evidence of the moderating effect of CESP on the SA quality–firm value nexus. Specifically, this study explores the joint effects of credibility and eco-efficiency on market confidence in sustainability information. The authors use a simultaneous equation model to capture the reciprocal association between SA quality and firm value, whereas prior studies on SA quality and market performance have frequently used single-equation regression. The authors also find that CESP positively moderates the relationship between SA quality and firm value. Including CESP and exploring the moderating impact of eco-efficiency on the SA quality–firm value relationship is a novel approach.

Although the association between sustainability assurance (SA) quality and firm value has been examined in previous studies, the moderating relationship is novel in this study and highlights the effect of corporate environmental sustainability performance (CESP) on the relationship between SA quality and firm value. This study aims to examine whether such an effect is strengthened or weakened by eco-efficiency, as measured by ISO 14001 certification, aggregate CESP score and each individual dimension of CESP (emission reduction [ER], resource reduction [RR] and product innovation [PI]).

The sample includes 40 companies in Euronext Paris with the largest market capitalisations (the Cotation Assistée en Continu 40 [CAC 40] index) from 2010 to 2020. The authors apply the feasible generalised least squares regression technique to estimate all the regression models. Because observed associations may be biased by reverse causation or self-selection, the authors use the instrumental variable approach and Heckman two-stage estimation.

The results show that SA quality had a positive and significant effect on firm value. Second, the authors demonstrate that CESP, as assessed by ISO 14001 certification, has a stronger interaction with assurance quality and acting as a moderator variable. Using the ASSET4 scores, an alternative proxy for CESP, the authors find inconsistent evidence regarding the impact of CESP attributes. The CESP and ER scores are homogeneous and have a positive effect on firm value. However, the PI and RR CESP attributes are not homogenous and do not have the same interactive effect on firm value. The results are robust to the use of an instrumental variable approach and the Heckman two-stage estimation procedure.

Policy implications: Regulators may be interested in the findings when considering current and future assurance requirements for sustainability reporting, and shareholders when considering SA as an investment choice criterion. The insights into and enhanced understanding of the incentives for obtaining high SA quality can help policymakers develop effective policies and initiatives for SA. Considering the possible improvements in sustainability performance when obtaining a high level of sustainability verification, governments need to consider mandating SA.

Firms receive clear confirmation of the importance of investing in SA quality. Financial markets do not evaluate SA dichotomously but reward companies with higher SA quality because of the greater credibility it provides. Firms should allocate a significant percentage of their annual budgets and other relevant resources to environmental training and development programmes to improve and maintain environmental performance. If they care about environmental issues, they must announce this by issuing sustainability reports and seeking assurance of the information disclosed. High-quality assurance not only has a significant effect on investors’ investment reliability judgements but also the perceived credibility of environmental performance fully moderates the effect of assurance on these judgements.

This study has social implications; the authors find that the French market rewards firms that provide a high-quality assurance to guarantee the integrity of their sustainability reports. Therefore, by incorporating environmental sustainability into their financial goals, a better assurance ultimately will urge firms to move from green washing to strategic goals, which is beneficial for society. Further, firms that focus on sustainability as part of their business strategy may attract employees who engage in green behaviours at work and create a friendlier and productive environment because it gives meaning to the work they do and keeps them engaged to the level needed to perform their jobs capably.

This study contributes to the literature by re-examining the relationship between SA quality and firm value. It also provides new evidence on the moderating effect of CESP on the SA quality–firm value nexus. Specifically, it explores the joint effect of credibility and eco-efficiency on market confidence in sustainability information.

Man has been seeking an ideal existence for a very long time. In this existence, justice, love, and peace are no longer words, but actual experiences. How ever, with the American preemptive invasion and occupation of Afghanistan and Iraq and the subsequent prisoner abuse, such an existence seems to be farther and farther away from reality. The purpose of this work is to stop this dangerous trend by promoting justice, love, and peace through a change of the paradigm that is inconsistent with justice, love, and peace. The strong paradigm that created the strong nation like the U.S. and the strong man like George W. Bush have been the culprit, rather than the contributor, of the above three universal ideals. Thus, rather than justice, love, and peace, the strong paradigm resulted in in justice, hatred, and violence. In order to remove these three and related evils, what the world needs in the beginning of the third millenium is the weak paradigm. Through the acceptance of the latter paradigm, the golden mean or middle paradigm can be formulated, which is a synergy of the weak and the strong paradigm. In order to understand properly the meaning of these paradigms, however, some digression appears necessary.

This study aims to evaluate the thermal performance of sodium alginate (SA) aerogel attached to nano SiO₂ and its radiative cooling effect on firefighting clothing without environmental pollution.

SA/SiO₂ aerogel with refractory heat insulation and enhanced radiative cooling performance was fabricated by freeze-drying method, which can be used in firefighting clothing. The microstructure, chemical composition, thermal stability, and thermal emissivity were analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analyzer and infrared emissivity measurement instrument. The radiative cooling effect of aerogel was studied using thermal infrared imager and thermocouple.

When the addition of SiO₂ is 25% of SA, the prepared aerogel has excellent heat insulation and a high radiative cooling effect. Under a clear sky, the temperature of SA/SiO₂ aerogel is 9.4°C lower than that of pure SA aerogel and 22.1°C lower than that of the simulated environment. In addition, aerogel has more exceptional heat insulation effect than other common fabrics in the heat insulation performance test.

SA/SiO₂ aerogel has passive radiative cooling function, which can efficaciously economize global energy, and it is paramount to environment-friendly cooling.

This method could pave the way for high-performance cooling materials designed for firefighting clothing to keep maintain the wearing comfort of firefighters.

SA/SiO₂ aerogel used in firefighting clothing can release heat to the low-temperature outer space in the form of thermal radiation to achieve its own cooling purpose, without additional energy supply.