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The purpose of this paper is to investigate a reliable evaluator of arc re-ignition and to develop a numerical tool for accurate prediction of arc behaviour of low-voltage switching devices (LVSDs) prior to empirical laboratory testing of real products.

Two types of interruption tests have been carried out in the investigation of re-ignition evaluators. Arc modelling tool coupled with the load circuit has been developed to predict arc characteristics based on conventional magnetohydrodynamics theory, with special attention given to Lorentz force acting on the arc column and surface phenomena on the splitter plate. The model assumptions have been validated by experimental observation of arc motion and current and voltage waveforms.

It is found that the exit-voltage across the switching device and the ratio of system to exit-voltage at the current zero point are reliable evaluators for prediction of re-ignition. Where the voltage ratio is positive, instantaneous re-ignition does not occur. Further, the probability of re-ignition is very low if the voltage ratio is in the rage of −1.3 to 0.

It is observed that the voltage ratio can be considered as a reliable global evaluator of re-ignition, which can be used for various types of LVSD test conditions. In addition, it is shown that arc modelling allows a good prediction of the current and voltage waveforms, arc motion as well as the exit-voltage, which can be used to obtain the evaluator of re-ignition.

This paper aims to present the mathematical formulations of a magnetic inverse problem for the electric arc current density reconstruction in a simplified arc chamber of a low-voltage circuit breaker.

Considering that electric arc current density is a zero divergence vector field, the inverse problem can be solved in Whitney space W² in terms of electric current density J with the zero divergence condition as a constraint or can be solved in Whitney space W¹ in terms of electric vector potential T where the zero divergence condition naturally holds. Moreover, the tree gauging condition is applied to ensure a unique solution when solving for the vector potential in space W¹. Tikhonov regularization is used to treat the ill-posedness of the inverse problem complemented with L-curve method for the selection of regularization parameters. A common mode approach is proposed, which solves for the reduced electric vector potential representing the internal current loops instead of solving for the total electric vector potential. The proposed inversion approaches are numerically tested starting from simulated magnetic field values.

With the common mode approach, the reconstruction of current density is significantly improved for both formulations using face elements in space W² and using edge elements in space W¹. When solving the inverse problem in space W¹, the choice of the regularization operator has a key role to obtain a good reconstruction, where the discrete curl operator is a good option. The standard Tikhonov regularization obtains a good reconstruction with J-formulation, but fails in the case of T-formulation. The use of edge elements requires a tree-cotree gauging to ensure the uniqueness of T. Moreover, additional efforts have to be taken to find an optimal regularization operator and an optimal tree when using edge elements. In conclusion, the J-formulation is to be preferred.

The proposed approaches are able to reconstruct the three-dimensional electric arc current density from its magnetic field in a non-intrusive manner. The formulations enable us to incorporate a priori knowledge of the unknown current density into the solution of the inverse problem, including the zero divergence condition and the boundary conditions. A common mode approach is proposed, which can significantly improve the current density reconstruction.

This paper presents the initial stage of a 3D finite element (FE) model of the electromagnetic field in the arc chamber of a current limiting miniature circuit breaker (MCB). The final objective of the model is to compute the magnetic forces on the arc, and predict the position of the arc at a series of discrete time steps. The trajectory of the arc calculated from the model will then be compared with experimental data recorded by a high speed arc imaging system (AIS) on a flexible test apparatus (FTA) designed to simulate the operation of a commercial MCB under laboratory conditions. By comparing the FE model of the arc behaviour with the actual arc images generated from the AIS an insight into the factors governing the motion of the arc can be gained. In particular the relative importance of the average flux density across the arc chamber is compared with the local flux density distribution at the arc roots. An understanding of the influence of the magnetic flux distribution can then be used to improve the magnetic design of the MCB to promote low immobility times and effective current limiting operation.

The purpose of this paper is to assess the impacts of GM crop adoption on the profitability of farms operated by young and/or beginning farmers and ranchers (YBFR).

This research uses weighted quantile regression analysis in conjunction with 2004‐2006 Agricultural Resource Management Survey to evaluate the impact of GM crop adoption on financial performance of farms operated by YBFR. The methodology employed in this study corrects for the simultaneity of technology adoption and farm financial performance.

As expected, the impact of GM crop adoption on profitability is positively affected by the scale of operation and leverage. On the other hand, off‐farm employment by “beginning” farmers has a negative impact on farm's profitability if they choose to adopt GM crops. Finally, quantile regression results from a farm household study shows that the model performs better at the higher quantile of the distribution.

This study helps to determine whether the adoption of GM crops increases the profitability of farms operated by “beginning” farmers. In addition, it explores the impact of other factors (such as farm, operator, demographic, and financial characteristics) on the profitability of farms operated by “beginning” farmers.

Computing the profitability of adoption decisions for YBFR will provide significant information to YBFR that they can use in constructing their farm operations strategic business plan and future decisions regarding farming operations.

Existing research does not examine the impact of GM crops adoption on farm profitability of YBFR. Furthermore, YBFR operators face significant challenges in making their operations financially viable, owing to lack of access to capital and land.

The purpose of this paper is to examine the rise in crossbred cow numbers in the US dairy herd. Methods used look at well managed herds to see if crossbreeding provides a management tool that producers are using to maintain profitability.

The authors estimate a Translog stochastic production frontier (SPF) for US dairy farms to examine the competitiveness of crossbred and non-crossbred dairy herds by system and region.

The bottom-line conclusion is that WM or highly efficient crossbred herds solidly compete on a financial basis with larger WM Western Holstein herds, the most technically efficient managed group, based on the SPF results in the authors’ study. The study finds that net return on assets for crossbred herds are not different from Western Holstein herds and that there is no significant difference in amount of milk per cow produced annually.

Because of a need to unmask the advantages of crossbreeding as a technology it was necessary to separate WM herds from poorly managed herds. That was done by frontier estimates that robustly ranked operation and corrected for endogeneity, tested for selectivity bias, and incorporated the NASS survey design.

For the first time, the 2010 Dairy Cost and Returns questionnaire version of the Agricultural Resource Management Survey (Dairy CAR) design allows researchers to expand survey observations to represent the vast majority of the US dairy farm population and to sort dairy farms into crossbred/non-crossbred herds.

The purpose of this paper is to present an integrated analysis of determining factors of farmers’ genetically modified (GM) technology adoption behavior, with a special emphasis on information acquisition, knowledge accumulation, product attributes and technology traits.

Extending the expected profit maximization framework into a random utility model which accommodates joint decisions of information acquisition and technology adoption, the authors use the full information maximum likelihood method to yield both consistent and efficient estimates. The model is applied to a field survey collecting a sample of 141 randomly selected bananas farmers.

The empirical results indicate information acquired through social network will increase the probability of adoption. Knowledge accumulation as depicted by education and farming experience is found to play a role in farmers’ technology adoption, whereas disease-resistant technology trait and flavor-enriching product attribute of GM bananas also appear to be important determinants for GM seeds adoption in Taiwan.

Empirical evidence supports significance of technology traits and product attributes in farmer's GM technology adoption, suggesting the close collaboration between industry, government and academia is the key to successful commercialization of GM crops.

Understanding the determinants of farmers’ GM technology adoption can serve as the basis for promoting new biotechnology, and thus can facilitate the establishment of tenable solutions to food security issues.

This paper is the first attempt to incorporate information acquisition into the behavioral analysis of GM technology adoption. The present study also extends previous literature by considering influential factors related to both consumers’ and producers’ preferences in modeling technology adoption.

In this work, commercial silver metal contacts welded on top of silver plated brass or brass substrates have been exposed to air rich in NaCl. Scanning electron microscopy and energy dispersive analysis of the exposed contact surfaces were performed to identify the corrosion by‐products on top of the silver contacts, suspending wafers, and welding materials. Surface corrosion products were mainly found to consist of small spherules of Cu‐Zn or Ag‐Cu compounds which cover the surface of the contact proper with low adhesion properties. They mainly originate from the underplating wafer or welding materials. Electrical characterization of the contacting materials was based on dc temperature overheat tests, current switching cycle tests, and energy storage during ac current excitation. The experimental results display that the operating environment is indeed a very significant parameter determining the overall performance of the electrical contacts. New design rules as well as material selection properties may have to be systematically considered to allow for electrochemical induced degradation in saline operating environments.

The purpose of this article is to document and evaluate patterns of nontraditional credit use among Wisconsin dairy farmers. Using a survey-based case study approach, this article analyzes farmer and farm characteristics, farmers’ utilization of credit and farmers’ perceptions of nontraditional lenders. The findings are connected to ongoing structural change in the dairy sector and economic theories of trade credit.

Data were collected using an incentivized online survey of Wisconsin dairy farmers distributed through existing university and industry networks. A total of 16 farmers completed the survey. The sample is treated as a focus group case study, and participants’ responses are examined using summary statistics and correlational analyses to describe emergent patterns in the industry.

Among survey respondents who utilize agricultural credit, nearly 80% (11 of 14) borrow from at least one nontraditional lender, and nontraditional credit comprises 17% of their total borrowing, on average. Much of this borrowing occurs through the financial arm of a vendor and is used to finance equipment or machinery purchases. Despite widespread use of nontraditional credit, no surveyed farmers preferred nontraditional lenders over traditional lenders.

This is the first study to analyze the use of nontraditional credit specifically among Wisconsin dairy farmers. Dairy farming is a capital-intensive endeavor, and recent structural change in the sector has increased surviving dairy farmers' demand for credit.

Over dependence on river/sea sand as building material has impacted the environment negatively. However, laterite, which is an environment-friendly indigenous building material in sub-Saharan Africa, has been less exploited as a suitable alternative. This paper aims to ascertain the optimum cement–laterite mix proportion at which laterite can be stabilized for production of walling units.

Using an experimental method, laterite was collected from three borrow pit sites. Sieve analysis was performed to determine the particle size distribution. Also, the degree of workability of the cement–laterite mix was ascertained using slump test. Compressive strengths were determined at cement stabilization percentages of 3%, 7% and 10% on 12 cubes of100 mm cast and cured for 14 and 28 days, respectively.

The results showed that the lateritic soil investigated, achieves its optimum strength in 28 days of curing, at a stabilization level of 10%. An average compressive strength of 2.41 N/mm2, which is 20.5% greater than the target strength, was achieved.

To meet the desired compressive strength of alternative walling units while achieving environmental sustainability and efficiency in production, cement stabilization of lateritic soils should become a recommended practice by built environment professionals in sub-Saharan Africa.

This paper is one of the first research works that attempts to determine the optimum level at which the abundant sub-Saharan laterite can be chemically stabilized for the production of non-load bearing walling units. This research promotes an environment-friendly alternative building material to sea sand, river sand and off-shore sand.

In the context of the trade war in full swing, the global supply chain systems have experienced a serious shock and become very vulnerable. The purpose of this paper is to explore the intertwining effects between the export-supporting subsidy policy and the import-deterring tariff policy to develop better insights for trade policy-making under the intra-industry-trade (IIT) conflicts. The research results may provide the trade policy makers and international businesses with better insights in making rational trade policy and business decisions.

Two-stage game-/bargaining-theoretical models for the dual competing international supply chains with a unilateral/bilateral tariff imposing or subsidy implementing under six different scenarios of IIT conflict are developed, analyzed and compared. On this basis, the corresponding numerical analyses are conducted to assess the impact of the tariff and subsidy policies and derive the trade policy implications and business insights.

The research results indicate that: (1) the bilateral subsidy implementing from both governments is the best policy for all stakeholders in two countries, which would lead to the highest profits, social welfare and consumer surplus than those of the other scenarios; (2) the bilateral tariff imposing of both governments is the worst policy for all stakeholders in two countries, which would lead to the lowest profits, social welfare and consumer surplus than those of the other scenarios; (3) the fair trade scenario without tariff imposing and subsidy implementing turns out to be the second-best trade policy for the governments. Under the World Trade Organization rule and fair-trade principles, the bilateral subsidy policy is not allowed in most of the cases. Thus, adopting a fair-trade policy may be the most appropriate trade policy for two trading countries.

The modeling approach developed for this study is original and innovative due to the following characteristics. First, based on three trade policy alternatives – fair trade, tariff imposing and subsidy implementing – of two generic governments under IIT conflict, nine different combinations of three policy alternatives are defined. Second, excluding the symmetrical combinations, six IIT conflict scenarios under various tariff/subsidy policy pairs ranging from no conflict to high conflict are assumed for two dual competing international supply chains. Third, a novel two-stage game-/bargaining-theoretical modeling approach is applied to investigate the optimal/equilibrium decisions regarding pricing, ordering quantity and their critical economic outcomes for all possible trade policy scenarios. Fourth, this study lays down a research foundation for the future trade conflict study using a game-theoretical modeling approach.