Developments in agriculture, industry, and urban life have caused the deterioration of water resources, such as rivers and reservoirs in terms of their quality and quantity. This includes the Saguling Reservoir located in the Citarum Basin, Indonesia. A review of previous studies reveals that the water quality index ( WQI) is efficient for the identification of pollution sources, as well as for the understanding of temporal and spatial variations in reservoir water quality. The NSFWQI (The National Sanitation Foundation water quality index) is one of WQI calculation methods. The NSFWQI is commonly used as an indi-cator of surface water quality. It is based on nitrate, phosphate, turbidity, temperature, faecal coliform, pH, DO, TDS, and BOD. The average NSFWQI has been 48.42 during a dry year, 43.97 during a normal year, and 45.82 during a wet year. The WQI helped to classify water quality in the Saguling Reservoir as “bad”. This study reveals that the strongest and most significant correlation between the parameter concentration and the WQI is the turbidity concentration, for which the coeffi-cient correlation is 0.821 in a dry year, and faecal coli, for which the coefficient correlation is 0.729 in a dry year. Both parameters can be used to calculate the WQI. The research also included a nitrate concentration distribution analysis around the Saguling Reservoir using the Inverse Distance Weighted method.

This paper presents a study on the effect of cleaning factors on the energy consumption of the cleaning process in a CIP system, and the correlation between single components of electricity necessary to perform this process and the cleanliness degree obtained. Studies were carried out in a laboratory cleaning station, wherein a plate heat exchanger contaminated with hot milk was included. The research program was developed according to a 5-level statistical plan. Based on the results, obtained with Experiment Planner 1.0, a regression function of energy requirement considering variables such as: cleaning time, temperature and flow rate of the cleaning liquid via the cleaned exchanger has been developed. Describing this relationship, linear and quadratic functions with double interactions were used. Significance level for the analysis was established at α = 0.05. Correlation analysis between components of the electricity necessary to perform the cleaning process (pump drive and heating of the cleaning agent) and the resulting degree of cleaning of heat exchanger plates was performed.

The paper analyzes the phenomenon of heat transfer and its inertia in solids. The influence of this effect on the operation of an integrated circuit is described. The phenomenon is explained using thermal analogy implemented in the Spice environment by an R-C thermal model. Results from the model are verified by some measurements with a chip designed in CMOS 0.7 μm (5 V) technology. The microcontroller-based measurement system structure and experiment results are described.