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Stiffened plates have been widely used in civil, marine, aerospace engineering. As a kind of thin-walled structure operating in complex environment, stiffened plates mostly undergo a variety of dynamic loads, which may sometimes result in large-amplitude vibration. Additionally, initial stresses and geometric imperfections are widespread in this type of structure. Furthermore, it is universally known that initial stresses and geometric imperfections may affect mechanical behavior of structures severely, particularly in dynamic analysis. Thus, the purpose of this paper is to study the stress variation rule of a stiffened plate during large-amplitude vibration considering initial stresses and geometric imperfections.

The initial stresses are represented in the form of initial bending moments applying to the stiffened plate, while the initial geometric imperfections are considered by means of trigonometric series, and they are assumed existing in the plate along the z-direction exclusively. Then, the dynamic equilibrium equations of the stiffened plate are established using Lagrange’s equation as well as aforementioned conditions. The nonlinear differential equations of motion are simplified as a two-degree-of-freedom system by considering 1:2 and 1:3 internal resonances, respectively, and the multiscale method is applied to solve the equations.

The influence of initial stresses on the plate, stresses during internal resonance is remarkable, while that is moderate for initial geometric imperfections. (Upon considering the existence of initial stresses or geometric imperfections, the stresses of motivated modes are less than the primary mode for both and internal resonances). The influence of bidirectional initial stresses on the plate’s stresses during internal resonance is more remarkable than that of unidirectional initial stresses. The coupled vibration in 1%3A2 internal resonance is fiercer than that in internal resonance.

Stiffened plates are widely used in engineering structures. However, as a type of thin-walled structure, stiffened plates vibrate with large amplitude in most cases owning to their complicated operation circumstance. In addition, stiffened plates usually contain initial stresses and geometric imperfections, which may result in the variation of their mechanical behavior, especially dynamical behavior. Based on the above consideration, this paper studies the nonlinear dynamical behavior of stiffened plates with initial stresses and geometrical imperfections under different internal resonances, which is the originality of this work. Furthermore, the research findings can provide references for engineering design and application.

Institutions, social norms and the nature of industrial relations vary greatly between Latin American and Western European countries. Such institutional and organizational differences might shape firms’ operational environment in general and the type of competition in product and labor markets in particular. The purpose of this paper is to identify and quantify industry differences in product and labor market imperfections in Chile and France.

The authors rely on two extensions of Hall’s econometric framework for estimating price-cost margins by nesting three labor market settings (LMS) (perfect competition (PC) or right-to-manage bargaining, efficient bargaining (EB) and monopsony). Using an unbalanced panel of 1,737 firms over the period 1996-2003 in Chile and 14,270 firms over the period 1994-2001 in France, the authors first classify 20 comparable manufacturing industries in six distinct regimes that differ in the type of competition prevailing in product and labor markets. The authors then investigate industry differences in the estimated product and labor market imperfection parameters.

Consistent with differences in institutions and in the industrial relations system in the two countries, the authors find regime differences across the two countries and cross-country differences in the levels of product and labor market imperfection parameters within regimes.

This study is the first to compare the type and the degree of industry-level product and labor market imperfections inferred from consistent estimation of firm-level production functions in a Latin American and a Western European country. Using firm-level output price indices, the microeconomic production function estimates for Chile are not subject to the omitted output price bias, as is often a major drawback in microeconometric studies of firm behavior.

Entrepreneurial knowledge spurs innovation and, in turn, generates a competitive advantage. This paper aims to explore if entrepreneurial knowledge combined with the attitude to innovate can overcome the key “imperfections” of the innovation process generated by dynamic, current technological progress in the knowledge-intensive sector. The “imperfections” identified in risk management, asymmetric information in the knowledge management process and hold-up problems can all disrupt collaborative partnerships and limit opportunities for innovation.

A theory-building approach is applied which offers a case study analysis of two small- to medium-sized enterprises (SMEs). These two SMEs operate in Europe but in two different territories: the UK and Italy. The study explores three key imperfections, risk management, asymmetric information in the knowledge management process and hold-up problems, which occur in the innovation process.

The entrepreneurs face these imperfections by adopting an open innovation model. Notwithstanding, both entrepreneurs had to deal with all “imperfections”, and their skills, attributes, attitude and aptitude allowed them to grow their business and continually develop new products. Therefore, the imperfections do not limit the innovative capacity of an entrepreneur but rather enhance their challengeable attitude. In this regard, the case studies induce a further analysis on entrepreneurial knowledge intertwined with entrepreneurial risk management and networking skills.

The empirical significance of the two cases does not allow theorisation. However, this research offers interesting results which can be strengthened by a comparative case study with other countries or deeper investigation by applying a quantitative approach.

By leveraging entrepreneurial knowledge, the imperfections noted in the innovation process can be overcome. Entrepreneurial knowledge is recognised as the main asset of an enterprise if it is combined with external talent or human resources. Entrepreneurs aim to develop innovative approaches and ideas through establishing both formal and informal collaborative partnership relationships which are used thanks to the entrepreneurs’ networking skills, knowledge and abilities.

Current procedures of buckling load estimation for thin-walled structures may provide very conservative estimates. Their refinement offers the potential to use structure and material properties more efficiently. Due to the large variety of design variables, for example laminate layup in composite structures, a prohibitively large number of tests would be required for experimental assessment, and thus reliable numerical techniques are of particular interest. The purpose of this paper is to analyze different methods of numerical buckling load estimation, formulate simulation procedures suitable for commercial software and give recommendations regarding their application. All investigations have been carried out for cylindrical composite shells; however similar approaches are feasible for other structures as well.

The authors develop a concept to apply artificial load imperfections with the aim to estimate as good as possible lower bounds for the buckling loads of shells for which the actual physical imperfections are not known. Single and triple perturbation load approach, global and local dynamic perturbation approach and path following techniques are applied to the analysis of a cylindrical composite shell with known buckling characteristics. Results of simulations are compared with published experimental data.

A single perturbation load approach is reproduced and modified. Buckling behavior for negative values of the perturbation load is examined and a pattern similar to a positive perturbation load is observed. Simulations with three perturbation forces show a decreased (i. e. more critical) value of the buckling load compared to the single perturbation load approach. Global and local dynamic perturbation approaches exhibit a behavior suitable for lower bound estimation for structures with arbitrary geometries.

Various load imperfection approaches to buckling load estimation are validated and compared. All investigated methods do not require knowledge of the real geometrical imperfections of the structure. Simulations were performed using a commercial finite element code. Investigations of sensitivity with respect to a single perturbation load are extended to the negative range of the perturbation load amplitude. A specific pattern for a global perturbation approach was developed, and based on it a novel simulation procedure is proposed.

This study aims to estimate total factor productivity (TFP) growth for the post-2008 period for selected industries in the manufacturing sector at NIC 3-digit. Total factor productivity growth (TFPG) estimates are based on the theoretical framework provided by studies such Hall (1988), Abraham et al. (2009) and Crepon et al. (2005) that incorporate market imperfection in labour and product market, thereby modifying the traditional TFP estimation as Solow Residual.

Based on the theoretical model that incorporates market imperfections in labour as well as product market in modifying the TFP estimates using the Levinsohn–Petrin framework of empirical estimation, the authors have calculated industry wise TFPG for 62 industries at NIC 3-digit level.

The study finds three distinct trends: first, there are considerable industrial disparities in productivity growth in terms of TFP. The estimates have been found to be higher than the conventional Solow Residual for most industries, indicating the role played by market imperfections in affecting the conventional measure of productivity growth. Second, estimates of bargaining power are found to be lower than those compared to the earlier estimates in Maiti (2013) for the Indian organised manufacturing case for 1998-2005. This observation is commensurate with the observation in recent years of a falling share in labour wage in total output in organised manufacturing sector. Finally, the study also found a statistically significant contribution of greater mechanisation on TFPG while an adverse effect of the rising dependence of organised manufacturing on contractual labour.

The role of market imperfections in measuring TFPG has been undertaken, and it has been found to be an important factor, as the estimated measures vary from the conventional measures of TFPG. Moreover, the study has considered a very recent period from 2008-2015 in estimating TFPG, as well as analysing the factors behind the trends in TFPG at industrial level.

Our economies are rapidly evolving toward being primarily service-driven, with information and communication as fundamental drivers for the service deployment. Strategic choices are increasingly driven by other parameters than the traditional goods-driven industrial type of economies. In this paper, the major drivers for making strategic choices in a competitive service economy are examined. It is shown how the competition in services based on information and communication technology (ICT) is competence-based. Competition aims at bringing additional value through services, but may also deploy specific techniques to stop value from leaking in particular business processes. Value creation and prevention of value leaks cannot just rely on the traditional material-based techniques, which are grounded in the strong tangible nature of the traditional economies. Today ICT-based services involve creative combinations of technologies, resources, and assets to answer as well as anticipate the growing demand for flexible solutions that create sustained added value. In this paper, the particular role of imperfections in service systems is explored, extending the well-known theories of information imperfections. Imperfections are not always solved but are sometimes even maintained in favor of sustained competitive advantage. Various ways to realize service rent are discussed with extensive examples. The concluding part of the paper points to some crucial service configuration issues, including the need for a sufficient degree of corporate-wide standardized service components and interfaces to address the growing demand for agility in competence-driven markets.

The paper aims to provide an investigation about the effect of some selected production parameters such as core yarn type, sheath sliver type and total yarn count factors on core spun vortex yarns' evenness, imperfection and tensile properties. Hence it is aimed to contribute to the literature in vortex spinning where there are limited works related to core-spun vortex spinning.

The paper evaluates the effect of core yarn type, sheath sliver type and total yarn count factors on yarn evenness, imperfections, hairiness and tensile properties. Completely randomised three-factor analysis of variance (ANOVA) was conducted in order to evaluate the effect of core yarn type, sheath sliver type and linear yarn density on core spun vortex yarns' evenness, imperfection and tensile properties at significance level of 0.05. SNK tests were also performed for observing the means of each parameter. Correlation analysis was also conducted to reveal some relationships between yarn evenness and yarn tensile properties.

In this paper, significant factors related to some production parameters affecting the core-spun vortex yarns' evenness, imperfection, hairiness and tensile properties were found.

There are limited works related to effect of selected production parameters on yarn evenness, Imperfections and Tensile Properties of Hybrid Vortex Yarns.

Several experimental and numerical studies were performed in the past to estimate buckling capacity of corroded tubular members. However, the effect of initial imperfections has not been properly considered in most of these earlier proposed formulas. Therefore, the main objective of this paper is to propose an accurate analytical formula to determine the buckling capacity of patched corroded tubular members.

Tubular members with initial geometrical imperfections can be regarded as beam-columns because of the combination of axial load and bending moment. The proposed formula is derived for a rectangular corrosion patch. The proposed formula is verified with results from finite element analysis of corroded tubular members and experimental results. The formula is also applied to an existing offshore jacket structure to highlight its significance and applicability. It is found that the buckling capacity of jacket members in splash zone reduces significantly with ageing. This reduction is around 29 and 14% for the selected brace and leg member respectively, during the design life. Finally, it is concluded that corrosion reduces the buckling capacity significantly and the proposed formula can be easily applied by practicing engineers to give an accurate and slightly conservative estimate the remaining buckling capacity.

The main finding is the new formula which accurately and conservatively estimate the buckling capacity of corroded tubular members. The proposed formula considers the secondary effect of both initial geometrical imperfections and shifting of centroid because of corrosion.

The proposed new formula is unique and original in that it considers both secondary effects from geometrical imperfections, reduction of cross-section from corrosion wastage and shifting of centroid because of corrosion. Finally, it is concluded that corrosion reduces the buckling capacity significantly and the proposed formula can be easily applied by practicing engineers to conservatively estimate the remaining buckling capacity and verify if further, more advanced estimations are needed.

Drawing on the extant literature that suggests marketing imperfections are an opportunity to create and establish a foundation for sustainable entrepreneurial prospects and sustainability, this study aims to delineate a marketing mix strategy for Indian medicinal and aromatic plant (MAP) resources to optimize the benefits derived from their existing MAP business and address its marketing imperfections.

A case study research design was used to investigate the MAP sector, and 37 in-depth interviews were conducted to collect the primary data. Given the study’s exploratory nature, an inductive approach was used for data analysis, and conventional qualitative content analysis was performed to analyze the data.

The findings reveal that a marketing mix strategy is relevant for linking MAP businesses to the country’s sustainable livelihood options, entrepreneurial prospects, resource management and the economy and for improving the sector’s global competitive position.

To the best of the author’s knowledge, this study is the first to explore and present a marketing mix strategy for Indian MAP resources. Thus, it extends the marketing and entrepreneurship literature regarding natural resource businesses to advance sustainable entrepreneurial prospects and sustainability. The study concludes by offering strategic clues for implementing the marketing mix strategy in the Indian MAP sector and businesses.

Experimental mid/large scale testing of ship-like stiffened panels in compression is a quite expensive exercise that is not standard. Numerical simulations are preferred instead. Because of being relatively inexpensive (cost and time wise), most authors perform an exhaustive design space exploration arriving at a significant number of runs. This work demonstrates that the buckling response with respect to the nondimensional slenderness ratios may well be fitted with nine runs per stiffener geometry.

Efficient derivation of buckling strength formulas for stiffened panels through the employment of design of experiments (DoE) and response surface methodology (RSM) combined with numerical nonlinear experimentation over the entire range of practical geometries.

The surrogate model developed for T-bar stiffeners predicts accurately enough the ultimate stress in the practical design area, while the surrogate models for angle bars and flat bars demonstrate difference between 10 and 30% from common structural rules (CSR).

To the authors' best knowledge, the statistical-based formal and rigorous approach of DoE and RSM to obtaining buckling surfaces for stiffened panels is performed for the first time. The number of required observations per stiffener type has not been addressed yet as each work selects its own sampling scheme without formal reasoning. This work comes to frame the number of observations for efficient surrogate model building.