A Decision-Making Model for Supplier Selection in Public Procurement

Public procurement is a multi-criteria decision-making (MCDM) problem that meets lexicographic preference to some extent. In this paper, a two-layer method that meets lexicographic preference selection was proposed to address the government procurement decision-making problem of multi experts in the fuzzy environment. The decision-making process of this model is divided into two steps. Firstly, attributes of multiple experts were collected according to their rights of speech, getting the comprehensive attribute preference order. Secondly, the program meeting lexicographic preference was decided based on the comprehensive attributes. Finally, the proposed model was applied to the firefighting cushion bidding case of Fire Station of A public security department. Results demonstrated that the proposed model is applicable to public procurement decision-making and can provide effective references to decision-making on government procurement

Dynamic Contact Angle on a Surface with Gradient in Wettability

The retention and drainage of water on heat exchangers is extremely important in air-conditioning, refrigeration, and heat-pumping systems. In this work, droplets of varying sizes sliding on an inclined heat exchanger materials with and without a wettability gradient are observed using a high-speed camera. The dynamic contact angles, the shape evolution and the velocity of the droplet are obtained by image processing. Aluminum and copper surfaces are examined and the gradient is created by partially treating the base surface. The hypothesis is that the momentum of a sliding droplet on a treated surface will push the droplet onto the part without any treatment, so that water retention and drainage can be improved with limited surface treatment. It is found that the dynamic contact angle, the shape evolution and the velocity can be very different for droplets sliding in a wettability-increasing direction when compared to those sliding in a wettability-decreasing direction. The results are very important for the design of specialized heat transfer surfaces operating under dehumidification or defrosting conditions

Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method.

Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm(2) at a current density of 3 mA/cm(2) when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm(2), and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work