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This paper aims to present the novel stacked machine learning approach (SMLA) to estimate low-cycle fatigue (LCF) life of SAC305 solder across structural parts. Using the finite element simulation (FEM) and continuous damage mechanics (CDM) model, a fatigue life database is built. The stacked machine learning (ML) model's iterative optimization during training enables precise fatigue predictions (2.41% root mean square error [RMSE], R² = 0.975) for diverse structural components. Outliers are found in regression analysis, indicating potential overestimation for thickness transition specimens with extended lifetimes and underestimation for open-hole specimens. Correlations between fatigue life, stress factors, nominal stress and temperature are unveiled, enriching comprehension of LCF, thus enhancing solder behavior predictions.

This paper introduces stacked ML as a novel approach for estimating LCF life of SAC305 solder in various structural parts. It builds a fatigue life database using FEM and CDM model. The stacked ML model iteratively optimizes its structure, yielding accurate fatigue predictions (2.41% RMSE, R² = 0.975). Outliers are observed: overestimation for thickness transition specimens and underestimation for open-hole ones. Correlations between fatigue life, stress factors, nominal stress and temperature enhance predictions, deepening understanding of solder behavior.

The findings of this paper highlight the successful application of the SMLA in accurately estimating the LCF life of SAC305 solder across diverse structural components. The stacked ML model, trained iteratively, demonstrates its effectiveness by producing precise fatigue lifetime predictions with a RMSE of 2.41% and an “R²” value of 0.975. The study also identifies distinct outlier behaviors associated with different structural parts: overestimations for thickness transition specimens with extended fatigue lifetimes and underestimations for open-hole specimens. The research further establishes correlations between fatigue life, stress concentration factors, nominal stress and temperature, enriching the understanding of solder behavior prediction.

The authors confirm the originality of this paper.

The purpose of this paper is to augment heat transfer rates of traditional rib-elements with minimal pressure drop penalties.

The novel geometries in the present research are conventional cylindrical ribs with rounded transitions to the adjacent flat surfaces and with modifications at their bases. All turbulent fluid flow and heat transfer results are presented using computation fluid dynamics with a validated v2f turbulence closure model. Turbulent flow characteristics and heat transfer performances in square channels with improved ribbed structures are numerically analyzed in this research work.

Based on the results, it is found that rounded transition cylindrical ribs have a large advantage over the conventional ribs in both enhancing heat transfer and reducing pressure loss penalty. In addition, cylindrical ribs increase the flow impingement at the upstream of the ribs, which will effectively increase the high heat transfer areas. The design of rounded transition cylindrical ribs and grooves will be an effective way to improve heat transfer enhancement and overall thermal performance of internal channels within blade cooling.

The novel geometries in this research are conventional cylindrical ribs with rounded transitions to the adjacent flat surfaces and with modifications at their bases. The combination of cylindrical ribs and grooves to manipulate the turbulent flow.

Degraded failures and sudden critical failures are quite prevalent in industries. Degradation processes commonly belong to Weibull family and critical failures are found to follow exponential distribution. Therefore, it becomes important to carry out reliability and availability analysis of such systems. From the reported literature, it is learnt that models are available for the situations where the degraded failures as well as critical failures follow exponential distribution. The purpose of this paper is to present models suitable for reliability and availability analysis of systems where the degradation process follows Weibull distribution and critical failures follow exponential distribution.

The research uses Semi-Markov modeling using the approach of method of stages which is suitable when the failure processes follow Weibull distribution. The paper considers various states of the system and uses state transition diagram to present the transition of the system among good state, degraded state and failed state. Method of stages is used to convert the semi-Markov model to Markov model. The number of stages calculated in Method of stages is usually not an integer value which needs to be round off. Method of stages thus suffers from the rounding off error. A unique approach is proposed to arrive at failure rates to reduce the error in method of stages. Periodic inspection and repairs of systems are commonly followed in industries to take care of system degradation. This paper presents models to carry out reliability and availability analysis of the systems including the case where degraded failures can be arrested by appropriate inspection and repair.

The proposed method for estimating the degraded failure rate can be used to reduce the error in method of stages. The models and the methodology are suitable for reliability and availability analysis of systems involving degradation which is very common in systems involving moving parts. These models are very suitable in accurately estimating the system reliability and availability which is very important in industry. The models conveniently cover the cases of degraded systems for which the model proposed by Hokstad and Frovig is not suitable.

The models developed consider the systems where the repair phenomenon follows exponential and the failure mechanism follows Weibull with shape parameter greater than 1.

These models can be suitably used to deal with reliability and availability analysis of systems where the degradation process is non-exponential. Thus, the models can be practically used to meet the industrial requirement of accurately estimating the reliability and availability of degradable systems.

A unique approach is presented in this paper for estimating degraded failure rate in the method of stages which reduces the rounding error. The models presented for reliability and availability analyses can deal with degradable systems where the degradation process follows Weibull distribution, which is not possible with the model presented by Hokstad and Frovig.

The purpose of this paper is to set up a new framework to enable direct modifications of volume meshes enriched with semantic information associated to multiple partitions. An instance of filleting operator is prototyped under this framework and presented in the paper.

In this paper, a generic mesh modification operator has been designed and a new instance of this operator for filleting finite element (FE) sharp edges of tetrahedral multi-partitioned meshes is also pro-posed. The filleting operator works in two main steps. The outer skin of the tetrahedral mesh is first deformed to round user-specified sharp edges while satisfying constraints relative to the shape of the so-called Virtual Group Boundaries. Then, in the filleting area, the positions of the inner nodes are relaxed to improve the aspect ratio of the mesh elements.

The classical mainstream methodology for product behaviour optimization involves the repetition of four steps: CAD modelling, meshing of CAD models, enrichment of models with FE simulation semantics and FEA. This paper highlights how this methodology could be simplified by two steps: simulation model modification and FEA. The authors set up a new framework to enable direct modifications of volume meshes enriched with semantic information associated to multiple partitions and the corresponding fillet operator is devised.

The proposed framework shows only a paradigm of direct modifications of semantic enriched meshes. It could be further more improved by adding or changing the modules inside. The fillet operator does not take into account the exact radius imposed by user. With this proposed fillet operator the mesh element density may not be enough high to obtain wished smoothness.

This paper fulfils an identified industry need to speed up the product behaviour analysis process by directly modifying the simulation semantic enriched meshes.

THE design of a flying boat hull is a compromise between the usually conflicting requirements of good performance on the water and in flight. For example, from aerodynamic considerations the hull should be without discontinuities, while for low water resistance when planing, discontinuities are necessary in the form of steps and chines, the former to localise the wetted area to that portion providing lift, and the latter to keep the spray as low as possible. Again, though the minimum air drag results from symmetry about the longitudinal axis, it is usual to curve the tail of a hull upwards to give the tail plane sufficient water clearance.

DRAWING technique comprises the methods of working in which hollow components are formed from plane material by means of a drawing die ring and a drawing punch and, if necessary, by using blank holders so that a more or less considerable movement of material takes place.

The paper aimed to summarize innovative rules of Chinese manufacturing enterprises, and put forward some insights in optimal allocation of innovation resources and enhancing the capability of indigenous innovation, so as to overcome the innovation dilemma.

Having diagnosed the current research of innovation flows, the authors defined the concept and stated characteristics of mainstream and new‐stream innovation. Innovation life cycle theory and technology trajectory theory were used to map two evolution patterns of mainstream and new‐stream innovation. It took weeks to stay in firms to obtain original data and interview managers, engineers, and mechanists. From the case study the authors proposed the improvement projects and opportunities for firms to overcome the “innovation dilemma”.

In the indigenous innovation process, enterprises should breed new‐stream innovation as they strengthen the mainstream innovation, view the new‐stream technology as the innovation direction, and fulfill the constant innovation in the convergent innovation and replace evolution process. Meanwhile, enterprises should take precautions both to expand and develop, and fulfill technology transition and innovation upgrade through convergent innovation. Furthermore, firms' convergent innovation, which will finally achieve the “projects‐talents‐products‐markets” collaborative innovation, should be clear about target market and project‐oriented, take the product as the carrier, and be committed to cultivate creative talents and innovative teams.

This paper enriches the existing theory on indigenous innovation by introducing the new concept of mainstream and new‐stream innovation. The findings would help firms to jump out from the innovation morass.

In this chapter, we theorize about online freelancers’ approaches to work flexibility. Drawing from an ongoing digital ethnography of US-based online freelancers pursuing work on digital platforms, our data question the common conceptualizations around the flexibility of online freelancing. We posit that the flexibility of where to work, not when to work, is the most important attribute of their work arrangement. Our data show (1) the online freelancers in our study prefer the stability and sustainability of full-time work over freelancing when both are offered as remote options; (2) full-time remote employment increases these workers’ freelancing control / flexibility; (3) these workers keep freelance work options open even as they transition to more permanent full-time work arrangements. We discuss how these findings relate to workplace culture shifts and what this means for contemporary working arrangements. Our insights contribute to the discourses on knowledge-based gig work and for what it means to study individuals online.

This study aims to introduce an important temporal dimension to the research on institution and entrepreneurship in the transition period. This study develops the concept of pre-reform institutional embeddedness, and explores its impact on entrepreneurial reinvestment of private firms in China’s transition economy.

The authors used secondary data of a nationally representative sample of China’s private firms collected in the early days of the institutional transition period and applied ordinary least squares regressions and the Baron and Kenny approach to test the theoretical model.

Pre-reform institutional embeddedness has a negative impact on entrepreneurial reinvestment of private firms in the transition period. This relationship is mediated by guanxi-induced employment, such that pre-reform institutional embeddedness promotes guanxi-induced employment, which in turn discourages a private firm to reinvest. Additionally, the negative impact of guanxi-induced employment on entrepreneurial reinvestment is reduced when decentralization of decision-making is used.

First, entrepreneurs should be aware of pre-reform institutional embeddedness’ negative influence on firms’ risk-taking abilities and incentives. Private firms already constrained by this connection could alleviate the negative impacts through a widespread delegation of decision-making authority. Second, policymakers should be cautious about improper government-business relationships, which may discourage private firms from fully pursuing entrepreneurial growth opportunities.

This paper makes theoretical contributions to the literature on entrepreneurial reinvestment, embeddedness perspective of entrepreneurship and imprinting theory.

FIG. 67: The by‐work for fixing the cores (a) and (b) is complicated owing to the undercutting (u) and the projection (p). The joint securing of both cores is difficult. The cores or the mould are easily damaged. The necessary patchwork means additional expense.