Search results

The purpose of this paper is to build a warranty cost model for consumer electronics with short lifecycle and frequently upgraded process in generations. Meanwhile, a new warranty service method of replacing the failed old generation (OG) products by new generation (NG) products is proposed to cease the service capability for the OG products from manufacturers’ viewpoint.

A model is built to find an optimal time to switch to the new warranty service method to minimize the warranty cost of the OG products. The inventory cost of spare parts of OG products for warranty, repair cost and manufacturing cost of NG products are taken into account. Meanwhile, a mixed strategy is studied by providing options to customers for replacing their failed OG products with NG products by paying a discounted price of the OG products. Moreover, numerical experiments are conducted to test the effects of different parameters on the optimal solutions.

Solutions to the proposed model are discussed with analytic method and it is proved that the optimal solution exists in the considered situations. The mixed strategy considering the willingness of customers can result in the reduction of the warranty cost.

This paper analyzes the situation that more than one generations of products are in the marketplace simultaneously. Furthermore, this work makes a useful contribution for manufacturers to decrease their warranty cost by changing the service method, and provides the optimal warranty strategy for manufacturers considering the willingness of customers.

The purpose of this paper is to examine the status of the supply reliability of groundwater irrigation, and discuss how it is affected by climate change and tubewell density in rural China.

This study is based on a nine-province village survey and secondary climate data. A Tobit model (or censored regression model) was used to estimate the determinants of supply reliability of groundwater irrigation.

Results show that the supply reliability of groundwater irrigation was 89 percent on average in the past three years. The non-linear relationship in the econometric results revealed that the 30-year annual temperature significantly influenced the supply reliability of groundwater irrigation. When the temperature rises above the turning point (6.30°C), it shifts from a positive to a negative relationship with the supply reliability of groundwater irrigation. The 30-year annual temperature in eight of the nine provinces (i.e. except for Jilin Province) was higher than the turning point. If the temperature increases by 20°C in the future, other factors being constant, the supply reliability of groundwater irrigation will decline by 20 percent. However, if precipitation increases by 10 percent, the supply reliability of groundwater irrigation could improve by 3 percent, while reducing precipitation by 10 percent will lower the supply reliability of groundwater irrigation by 3 percent. Increasing the density of tubewells considerably improves the supply reliability of groundwater irrigation. However, although increasing the density of tubewells may yield enough groundwater for irrigation, this one-sided approach raises sustainability concerns.

Although increasing the density of tubewells may ensure that enough groundwater is available for irrigation, such a conclusion is one sided, and sustainability concerns should be raised in assessing this method of creating supply reliability.

This paper improves the understanding of the impact of climate variables on agriculture irrigation and water supply reliability in the micro scale, and provides a scientific basis for relevant policy making.

This paper aims to evaluate innovation capability of companies based on comprehensive methods.

This paper used principal component analysis (PCA), kernel principal component analysis (KPCA) and principal component cluster (PCC) analysis to analyze the listed companies’ innovation capability. On these bases, mean method, Borda method, Copeland method, alienation coefficient method and fuzzy Borda method were used separately for the comprehensive evaluation.

The results show that the comprehensive evaluation can overcome the shortage of the single method and improve the reliability of the innovation ability evaluation. In addition, the method also reveals that the innovation ability of the listed companies is closely related to the innovation investment and their industry and further regional economic development level of each province (city and area).

This paper uses PCA, KPCA and PCC to evaluate and study their innovation ability. On the basis of these, five methods (mean method, Copeland method, Borda method, divorced coefficient method and fuzzy Borda method) are applied respectively to combine the sort results of PCA, KPCA and PCC. The results show that combination methods have better theoretical and practical significance for innovation ability.

The purpose of the paper is to show the corrosion effect of benzotriazole in comparison with iron phosphate (PFe) coating as a sealer for the PFe layer in carbon steel paint pre-treatment and to show its ecological advantages as a more environment-friendly inhibiting compound than PFe.

Samples of carbon steel (SAE 1010) were phosphated in two baths, one containing iron PFe and PFe and BTAH (PFe + BTAH). Anodic potentiostatic polarization curves and electrochemical impedance spectroscopy were used to evaluate the corrosion resistance of phosphated carbon steel in 0.1 molL−1 H₂SO₄, 0.5 molL−1 NaCl and 0.1 molL−1 NaOH. The phosphate layers obtained were analyzed by infrared spectroscopy. Surface observation by scanning electron microscopy (SEM) showed that the PFe and PFe + BTAH layers are deposited as crystals with granular morphology. The electrochemical results showed that the PFe + BTAH coating was more effective in corrosion protection of the carbon steel.

This paper presents the application of benzotriazole as post-treatment of PFe-coated carbon steel. The results show that benzotriazole improves the phosphate layer properties. The SEM micrographs showed that the layer formed in PFe and PFe + BTAH baths consists of grain-like crystals, and infrared results revealed the BTAH presence in PFe phosphate. The corrosion resistance results showed higher efficiency associated to the PFe + BTAH phosphate layer relative to that of PFe. From the present study, results can be concluded that BTAH can be used as a post-treatment for PFe phosphate coating.

This paper deals with the corrosion resistance and surface carbon steel characterization of a new sealer for PFe coating, which has been prepared for this study and was never tested previously. These are candidate materials for substitution of chromium sealer. The BTAH sealer presents environmental and corrosion resistance advantages when compared with the post-treatment based on chrome. Although BTAH improves PFe layers’ properties, it is the worst phosphate coating. This manuscript has never been previously submitted and deals with original results.