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This paper aims to present a comparison of numerical methods for determining the contact pattern of Gleason-type bevel gears. The mathematical model of tooth contact analysis and the finite element method were taken into consideration. Conclusions have been drawn regarding the usefulness of the considered methods and the compatibility of results. The object of the analysis was a bevel gear characterised by an 18:43 gear ratio and arc tooth line, and manufactured according to the spiral generated modified-roll method.

The mathematical model of tooth contact analysis consists of both the mathematical model of tooth generating and the mathematical model of operating gear set. The first model is used to generate tooth flanks of the pinion and the ring gear in the form of grids of points. Then, such tooth surfaces are used for the tooth contact analysis performed with the other model. It corresponds to the no-load gear meshing condition. The finite element method model was built on the basis of the same tooth flanks obtained with the former model. The commercial finite element method software Abaqus was used to perform two instances of the contact analysis: a very light load, corresponding to the former no-load condition, and the operating load condition. The results obtained using the two models, in the form of the contact pattern for no-load condition, were compared. The effect of heavy load on contact pattern position, shape and size was shown and discussed.

The mathematical models correctly reproduce the shape, position and size of the contact pattern; thus, they can be reliably used to assess the quality of the bevel gear at the early stage of its design.

Determination of the correct geometry of the flank surfaces of the gear and pinion teeth through the observation of contact pattern is a fundamental step in designing of a new aircraft bevel gear.

A possibility of the independent use of the mathematical analysis of the contact pattern has been shown, which, thanks to the compatibility of the results, does not have to be verified experimentally.

The finite element method has been increasingly applied in stress, thermal and dynamic analysis of gear transmissions. Preparing the models with different design and modification parameters for the finite element analysis is a time-consuming and highly skilled burden.

To simplify the preprocessing work of the analysis, a parametric finite element modeling method for spur and helical gears including profile and lead modification is developed. The information about the nodes and elements is obtained and exported into the finite element software to generate the finite element model of the gear automatically.

By using the three-dimensional finite element tooth contact analysis method, the effects of tooth modifications on the transmission error and contact stress of spur and helical gears are presented.

The results demonstrate that the proposed method is useful for verifying the modification parameters of spur and helical gears in the case of deformations and misalignments.

The purpose of this article is to present a method for the analysis of the quality of the bevel gear at the development level.

A non-commercial aircraft bevel gear design support system was developed. The system utilises matrix and vector calculi to model the technological machining systems and to analyse the contact of the designed pair. Both the technological model and the design model offer the possibility of manipulating the calculated parameters. This enables independent selection of the pinion/gear engagement, making it possible to achieved the desired contact pattern (its shape, position and size) and/or minimise motion transmission deviation. This article presents an analysis of the meshing of the aircraft transmission designed in two variants.

The newly developed non-commercial transmission design support system offers the capability to freely adjust mesh quality indicators. The first step is to perform automated technological calculations for a specific geometry of gear members, on the basis of which gear and pinion flanks are developed. Then, numerical models of tooth flanks are configured in the designed pair, and tooth mesh quality is verified. Quality indicators are provided in the form of summary contact pattern and the motion graph. In the subsequent step, changes are made to basic geometry of pinion tooth flank. After satisfactory mesh indicators have been reached, the transmission is tested for assembly errors and additional corrections are made to the geometry of the pinion tooth surface, as required. The above methodology guarantees that the assumed quality indicators are achieved on the physically cut transmission.

Fast preparation of the technology with guaranteed high mesh quality is a significant factor in the competitiveness of an industrial plant which implements a new bevel gear in its manufacturing activities.

The visualisation of the results of the use of the application allows the user to easily interpret the analysed contact pattern and take appropriate decisions as to the necessity of making corrections.

This paper aims to present a novel and cost-effective optical biosensor design by simple preparation method for detection of “parathion-methyl,” which is a model pesticide pose to public health and the environment.

The optical enzyme biosensor (TCA) for detection of pesticide “parathion-methyl” was developed on the basis of immobilization of tyrosinase enzyme on chitosan film by adsorption technique. The analytic performance of TCA was investigated by measuring its activity with Ultraviolet (UV) visible spectrophotometer.

Uniform porous network structure and protonated groups of chitosan film provided a microenvironment for tyrosinase immobilization evident from Fourier transform infrared (FTIR) spectroscopy and Atomic Force Microscopy analysis. TCA has a wide linear detection range (0-1.03 µM) with high correlation coefficient and it can detect the parathion-methyl concentration as low as 159 nM by noncompetitive inhibition kinetics. Using the TCA sensor both for ten times and at least 45 days without a significant loss in its activity are the indicators of its good operational and storage stability. Moreover, TCA can be applicable to tap water, providing a promising tool for pesticides detection.

This is the first time to use the in situ analytical technique that can improve the performance of optical enzyme sensor provided to control the pesticide residue better with respect to traditional techniques. The effect of organic solvents on the performance of optical enzyme biosensor was investigated. Inhibition kinetic of the solvents rarely encountered in literature was also studied besides the pH and temperature tolerance of the optical biosensor.

Despite the recent growth of the do-it-yourself market, very little is known as to how or why individuals actually choose to engage in prosumption behavior. The purpose of this study is to specifically examine the decision process of actors when determining the level of resource commitment and integration necessary to prosume or consume a service, thus offering insights to both managers and academics alike.

A multi-method study using both qualitative and quantitative research examines the decision of actors to consume or prosume a service. A conceptual model is presented and tested.

The results identify the primary drivers individuals considered when evaluating the resource commitment necessary for a make or buy decision. This research offers empirical support for the application of transaction cost analysis as an appropriate theoretical explanation of how actors decide to prosume or consume a service. The authors further suggest, based on these findings, that transaction cost analysis is a viable middle-range theory to explain the commitment and sharing of resources between actors engaged in co-production within the perspective of a service-dominant logic.

Future research is needed to identify opportunities for hybrid models that consider the appropriateness of these findings within larger service networks, as well as potential moderating or mediating influences of the direct effects identified and investigated.

This study offers an initial attempt to provide a theoretical explanation for the resource integration decisions (e.g. make or buy) faced by individuals in a growing segment of the economy. The findings enable better informed strategies to be identified by both service providers and retailers.

This paper aims to provide a transaction cost analysis (TCA) perspective to exporting firms' selection of foreign markets and the performance consequences of this international market selection (IMS) decision. This paper proposes a conceptual framework that hypothesizes the relationship between transaction cost factors, IMS and export performance.

This paper tests the proposed framework with a database of Chinese manufacturing firms using regression models and controlling for possible endogeneity. The endogeneity issue may arise due to IMS being influenced by unobserved industrial/firm attributes.

The results show that transaction cost factors are able to explain IMS. Furthermore, firms whose decisions have incorporated transaction cost factors perform significantly better than their rivals.

Understanding transaction costs helps decision-makers formulate more efficient IMS strategy to achieve superior export performance. Future research on IMS may examine “passive exporting”, i.e. exporting initiated by overseas buyers, consider the role of institutional distance and use other approaches toward cultural distance-based IMS.

This study adds a new theoretical underpinning for IMS by developing a framework based on TCA, and thus broadens the applications of TCA into IMS. Our empirical results support this extension.

The purpose of this paper is to examine a US retailer's decision to backward‐integrate its supply channel for global sourcing, based on the framework adapted from transaction cost analysis (TCA).

The conceptual framework was developed based on the past literature. A survey method was employed to collect the data from apparel retail firms engaging in global sourcing. Confirmatory factor analysis and ordinal regression analysis were used to diagnose the quality of data and to test hypotheses.

A retail firm avoids backward integration when facing high volume fluctuation and high country risk combined with asset specificity, while it favors the integration when perceiving high asset specificity, socio‐cultural distance, free‐ride potential, and sourcing volume. Great experience also leads to backward integration not only as a main factor, but also as a moderator reinforcing the effects of asset specificity and uncertainty on integration.

Although transaction costs associated with foreign procurement are highly significant, little attempt has been made so far to apply TCA to understand sourcing governance decisions, in particular those by retailers – important participants in the current landscape of global sourcing. This study fills this gap. This study also examines the role of import volume, experience, and free ride potential to provide a more comprehensive understanding of sourcing governance decisions by retailers.

Reveals the possible influence of trichloroethylene (TRI) and tetrachloroethylene (perchloroethylene, PER) via drinking water on the body burden resulting from a study of 55 subjects with no known solvent exposure, selected from the residents of the city of Zagreb. TRI and PER were determined in blood and their metabolite trichloroacetic acid (TCA) in plasma and urine. Drinking water samples were also analysed for TRI and PER. TRI concentrations in the blood ranged from <0.015‐0.09 μg/L, PER <0.010‐0.239 μg/L, TCA in plasma 8.6‐123.97 μg/L, in urine 1.67‐85.18 μg/24 h, TRI in drinking water 2.58‐22.93 μg/L and PER 0.63‐7.33 μg/L. Correlation analyses reveal significant relationships between TRI and PER in blood (r = 0.428; p = 0.0014), TRI and PER in drinking water (r = 0.767; p = 0.0000), TCA in urine and TCA in plasma (r = 0.629; p = 0.0000), ln TRI in drinking water and ln TCA in plasma (r = 0.322; p = 0.0164) and urine (r = 0.348; p = 0.0093), ln PER in drinking water and ln TCA in plasma (r = 0.370; p = 0.0055) and urine (r = 0.345; p = 0.0098). The latter quantitative relationships between both ln TRI and ln PER in drinking water relate to ln TCA in plasma and urine and may indicate TCA as a possible biologic marker of environmental exposure to TRI and PER.

A transaction cost analysis model of the situations in which small knowledge‐intensive firms use multiple distribution channels to serve a foreign market is developed. The central argument is that integrated modes are generally preferred, as they facilitate protection of knowledge‐based assets and the provision of high levels of customer service and support. However, it is hypothesised that either plural or hybrid selling may be used, if assets can be protected in other ways, as a response to environmental diversity, when sales volumes are sufficient to support multiple channels, and in relatively mature markets, where sales growth has started to plateau. Data gathered from Canadian software developers generally support these propositions. The results help the managers of knowledge‐intensive firms to identify some of the circumstances in which multiple export channels might be deployed to enhance sales performance in a foreign market.

This paper aims to optimize the operating condition of mechanical parts, whose working surfaces have macro-crack defects, and surface wear properties with macro-cracks are assessed through experimental investigation.

Macro-cracks perpendicular to the direction of sliding were manufactured on discs by electric discharge machining. Tribological tests under oil lubrication were conducted on a ball-on-disc test rig. Their wear processes were monitored with on-line visual ferrography. The cross-sectional profile and morphology of the wear track were analyzed using a T200 profilometer and a scanning electron microscope, respectively. Effects of different crack numbers and various applied normal loads on the wear behavior were studied.

The macro-cracks tend to promote plastic deformation on the contact disc surfaces, and material plastic deformation of the crack edges varies with the magnitude of applied normal loads. Relationship of the duration of running-in period and root mean square index of the particle coverage area with the numbers of crack is approximately linear.

The wear properties of surfaces with macro-cracks were assessed with various crack numbers and with different applied normal loads, and the relationship between the index of particle coverage area and the wear rate was established.