This paper is to deal with Mond-Weir duality and Wolfe duality for constrained set-valued optimization problems in terms of conedirected Clarke derivatives. Firstly, necessary and sufficient optimality conditions for constrained set-valued optimizations in terms of cone-directed Clarke derivatives for the cone-semilocally convex like maps are investigated. Then, the Mond-Weir duality and Wolfe duality for a constrained set-valued optimization and their weak duality, strong duality and converse duality are considered. TÓM TẮT Bài báo này khảo sát bài toán đối ngẫu dạng Mond-Weir và Wolfe cho bài toán tối ưu đa trị có ràng buộc sử dụng đạo hàm đa trịClarke theo hướng nón. Trước hết, điều kiện tối ưu cần và đủ cho bài toán tối ưu đa trị có ràng buộc sử dụng đạo hàm đa trị Clarke theo hướng nón cho lớp hàm tựa lồi nửa địa phương được khảo sát. Sau đó, bài toán đối ngẫu dạng Mond-Weir và Wolfe cho bài toán tối ưu đa trị có ràng buộc và các tính chất về đối ngẫu mạnh, đối ngẫu yếu và đối ngẫu ngược được trình bày.

Study on the characteristics of salinity transport in 2D cross-section unconfined aquifer Groundwater salinity is currently a problem of a great concern in coastal areas of Vietnam. The characteristics of the salinity transport in 2-dimensional cross section of aquifer under different boundary conditions, boundary values and groundwater flow velocity field have been determined through finite element modeling application. Two aquifer types have been considered: confined aquifer with constant velocity in space and unconfined aquifer with variable horizontal and vertical velocity in space. The influence of the boundary types and boundary values on the salinity transport had been concentrated and analyzed. The results of the salinity distribution configuration within the aquifer have significance in directional research of the actual problems. The similar salinity distribution of two cases: constant specified boundary and variable specified boundary the average of which is equal to the constant specified value had given opportunity to simplify complicated actual problems for utilization of simpler models.