The influencing factors of Harbin (China) residents’ satisfaction with municipal solid waste treatment

China is experiencing an enormous increase in municipal household solid waste (MHSW) generation and is facing multiple problems associated with the treatment of MHSW. This paper analyses factors affecting residents’ satisfaction with MHSW treatment performance. Six factors were identified by the Delphi method: (a) pick-up frequency by waste collection vehicles, (b) fund supply situation, (c) charging standard for waste treatment, (d) waste bin arrangement, (e) laws and regulations, (f) publicity and education. We examine the significance of these six influencing factors, estimating binary logistic regression models. Data for this study are derived from the survey responses of 469 households in Harbin, one of the largest cities in northeast China. The results indicate that ‘pick-up frequency by waste collection vehicles’ is ranked the first and most important determinant of Harbin residents’ satisfaction with MHSW treatment; this is closely followed by ‘publicity and education’. The third and fourth significant influencing factors, respectively, are ‘fund supply situation’ and ‘charging standard for waste treatment’. The last two factors are ‘laws and regulations’ and ‘waste bin arrangement’. By understanding the influence of various factors on residents’ satisfaction, this study aims to help in designing an effective waste management system to reduce the cost of MHSW management, and to raise the residents’ satisfaction with municipal solid waste treatment. Based on the research findings, we advocate that establishing a reasonable waste transport (pick-up) system as well as strengthening publicity and education of waste management are key to improving residents’ satisfaction with the MHSW treatment performance.

PPE: at the heart of dentistry

The past four months have been a tumultuous time for the dental sector. But as practices prepare to go back to work, what is the PPE supply situation?

Temporal and spatial variation of hydrological condition in the Ziwu River Basin of the Han River in China

The middle route of South-To-North Water Diversion in China transfers water from the Han River and Han-To-Wei Water Diversion project of Shaanxi Province will transfer water from the Ziwu River, which is a tributary of the Han River. In order to gain a better understanding of future changes in the hydrological conditions within the Ziwu River basin, a Mann–Kendall (M–K) trend analysis is coupled with a persistence analysis using the rescaled range analysis (R/S) method. The future change in the hydrological characteristics of the Ziwu River basin is obtained by analysing the change of meteorological factors. The results show that, the future precipitation and potential evaporation are seasonal, and the spatial variation is significant. The proportion of basin area where the spring, summer, autumn and winter precipitation is predicted to continue increase is 0.00, 100.00, 19.00 and 16.00 %, meanwhile, the proportion of basin area that will continue to decrease in the future respectively will be 100.00, 0.00, 81.00 and 74.00 %.The future potential evapotranspiration of the four seasons in the basin shows a decreasing trend. The future water supply situation in the spring and autumn of the Ziwu River basin will degrade, and the future water supply situation in the summer and winter will improve. In addition, the areas with the same water supply situation are relatively concentrated. The results will provide scientific basis for the planning and management of river basin water resources and socio-hydrological processes analysis.

Key Figures for Production Control in Non-Ferrous Melting and Die-Casting Plants Based on the Assessment of the Operating State

The study focuses on the examination and development of simulation based measures to increase the energy efficiency and productivity in the non-ferrous melting and die-casting industries. The high energy consumption of gas-fueled melting furnaces is caused by production fluctuations in the foundry. Currently the control of the operating processes is decentralized and based on empirical process experience and inaccurate information of the operating state. The acquisition of the plant wide supply situation of the die casting machines with liquid aluminum is an essential condition for solving the problem of inefficient working melting furnaces. Their representation is grounded on specially defined key figures.In a first step the filling levels of the different liquid aluminum sources (melting furnaces) are considered as one unit as well as the filling levels of the different liquid aluminum sinks (die-casting machines). This assumption leads to the so called storage distribution key figure which describes the current supply situation of the die casting plants with liquid aluminum. This single key figure is able to assess the complex plant wide supply state. This key figure allows the real time evaluation of the operating state (production safety). Another important key figure is the residual running time of the die casting machines. Both key figures can be used for controlling the operating processes, too. A simulation is needed in order to analyze these operating processes because otherwise it would interfere with the real production process. The simulation of the complete material flow of the aluminum starts with its delivery in solid and liquid form, continues with the melting in furnaces and leads to the production process in the die casting machines. Energetic key figures such as the gas consumption and the specific melting rate of the melting operation can be determined by bidirectional coupling with a physically based energy model of the melting furnaces. The simulation model was validated by measured data obtained in an industrial plant.The storage distribution key figure and the residual running time key figure can be used in order to provide Smart Services to increase energy efficiency and productivity in specific operating states. Adjusting the cleaning times of the melting furnaces or controlling the fork lift trucks are potential examples. The results of initial simulations show the effects of different control measures based on these key figures. Smart Services in real operation can be implemented as an assistance system but for the implementation in real operation a central data processing is indispensable prerequisite.

Substitution of Rare Earths in Magnesium Alloys

Magnesium alloys containing rare earth elements have better properties in terms of of formability, strength and corrosion resistance. Due to the tight supply situation these elements should be partially or complete substituted, for example by calcium. Microstructural studies of casted alloys of new compositions, and the influence of various heat treatments on their microstructure are investigated. The mechanical properties of the rolled materials are also presented and discussed. The works presented in this paper are results of the ongoing BMBF project SubSEEMag.