Water plays an essential part in human life. In our daily activities, water is something we must consume for our survival. As one of the largest seawater resources country in the world does not guarantee Indonesian citizens of having pure water to consume. Since, most of the water is already polluted by factories, industries and households. The needs of pure water are increasingly needed as the human population gradually increased. One of the technology to produce pure water is solar distillation. This research aims to find out the water productivity results and the efficiency of glass cover cooling by flowing water over the glass cover on passive double slope solar still. The results showed that the actual and theoretical water productivity calculation for this method are 4,36 liters and 7,57 liters. The efficiency for actual and theoretical of the system 52,32% and 90,88% respectively.

Fresh water plays a role and is responsible for life. The need for fresh water continues to increase due to its use in various fields of life, such as agriculture, industry and population. To prevent water shortages, it is very important to show the gap between the demand and supply of drinking water by developing water purification technology. Solar power / solar energy (renewable energy sources) in the form of distillation is one of the most promising, simple, and economical technologies for the purification of salt and brackish water. double slope passive system with the addition of water-cooled glass outside with water diluted by a solar-powered DC pump from photovoltaics with no outer glass cooler.

Almost all hospitals schedule nurses' work shifts manually, which is not effective, mistakes in scheduling nurses in hospitals can make them not work optimally so that they are prone to making mistakes and will endanger every patient in the hospital. In the research will be proposed integer linear programming model and branch and bound method, the purpose of this study is to develop an optimization model of nurse scheduling problems at the hospital. The optimization model will minimize the total deviation of nurses' working days from the standard workdays, the optimization model implemented in hospitals is processed using LINGO software.