Hydrogen Production from Biomass and Organic Waste Using Dark Fermentation: An Analysis of Literature Data on the Effect of Operating Parameters on Process Performance

In the context of hydrogen production from biomass or organic waste with dark fermentation, this study analysed 55 studies (339 experiments) in the literature looking for the effect of operating parameters on the process performance of dark fermentation. The effect of substrate concentration, pH, temperature, and residence time on hydrogen yield, productivity, and content in the biogas was analysed. In addition, a linear regression model was developed to also account for the effect of nature and pretreatment of the substrate, inhibition of methanogenesis, and continuous or batch operating mode. The analysis showed that the hydrogen yield was mainly affected by pH and residence time, with the highest yields obtained for low pH and short residence time. High hydrogen productivity was favoured by high feed concentration, short residence time, and low pH. More modest was the effect on the hydrogen content. The mean values of hydrogen yield, productivity, and content were, respectively, 6.49% COD COD−1, 135 mg L−1 d−1, 51% v/v, while 10% of the considered experiments obtained yield, productivity, and content of or higher than 15.55% COD COD−1, 305.16 mg L−1 d−1, 64% v/v. Overall, this study provides insight into how to select the optimum operating conditions to obtain the desired hydrogen production.

Influence of Different Dielectrics on Process Performance for Electrical Discharge-Assisted Milling of Titanium Alloy

Electrical discharge-assisted milling (EDAM) is an effective method for machining titanium alloys according to previous research. In this study, the influence of three different dielectrics (kerosene, EDM oil, and deionized water) on the EDAM performance was studied. Experimental studies reveal the influence of different dielectrics by analyzing the discharged signal, surface morphology, and elemental composition of the electrode. The results show that kerosene and EDM oil have a higher discharge frequency than deionized water. After a long discharge time, carbides and debris were generated during the machining process, which affected the micro-hardness and the discharge stability of the machined material. In EDAM, EDM oil can produce the best surface quality, and the surface roughness value was 34.93%, 87.92%, and 121.68% higher than that of kerosene, deionized water, and conventional milling (CM), respectively.

Control of Deformation of Elastic Polymer-Abrasive Circles at their Wear

The article is devoted to the study of the wear intensity of elastic polymer-abrasive circles when processing the surfaces of parts made of high-strength aluminum alloys. Empirical dependencies of wear on cutting speed and tool deformation are obtained, on the basis of which method of tool deformation correction with long-term, continuous surface treatment is proposed. In practice, such a procedure is necessary due to the loss of process performance that occurs due to the reduction of tool deformation due to wear. The proposed technique allows to effectively control the finishing process as the tool is worn out.

Improvement of Risk Management Process in Space Product Development Through its Continuous Integration

Relevance. Nowadays, enterprises not only have to constantly introduce new products, but also to reduce development time, reduce costs, and improve the variety and quality of their products. In the product development process, risk management is too often underutilized and relegated to the background compared to product development planning and monitoring tools. Moreover, the measurement of process performance of risk management within product development is not defined and does not allow for comparison with peers or support continuous process improvement.The purpose of the study is to provide a framework for improving the risk management process performance in space product development. So that risk managers have the proper tools to monitor and understand where resources and efforts should be directed to improve the process.Results. This article identifies how to represent risk in product development and how to measure its impact on the performance of the risk management process in product development. Through a survey of key players in the Russian space industry, the study identifies different practices and needs in risk management, product development and performance measurement of these processes.Methods. Theoretical research methods: analysis, synthesis, classification, comparison, abstraction, generalization, modeling. Empirical method — survey: questionnaire survey. The key contribution of this study (to limit the usual delays and cost overruns in the space industry) is to establish specific characteristics and methods that can serve as a reference practice and basis for the future development of a tool that will assist in the evaluation of space development projects.