Helical deep hole drilling is a process frequently used in industrial applications to produce bores with a large length to diameter ratio. For better cooling and lubrication, the deep drilling oil is fed directly into the bore hole via two internal cooling channels. Due to the inaccessibility of the cutting area, experimental investigations that provide information on the actual machining and cooling behavior are difficult to carry out. In this paper, the distribution of the deep drilling oil is investigated both experimentally and simulatively and the results are evaluated. For the Computational Fluid Dynamics (CFD) simulation, two different turbulence models, i.e. the RANS k-ω-SST and hybrid SAS-SST model, are used and compared. Thereby, the actual used deep drilling oil is modelled instead of using fluid dynamic parameters of water, as is often the case. With the hybrid SAS-SST model, the flow could be analyzed much better than with the RANS k-ω-SST model and thus the processes that take place during helical deep drilling could be simulated with realistic details. Both the experimental and the simulative results show that the deep drilling oil movement is almost exclusively generated by the tool rotation. At the tool’s cutting edges and in the flute, the flow velocity drops to zero for the most part, so that no efficient cooling and lubrication could take place there. In addition, cavitation bubbles form and implode, concluding in the assumption that the process heat is not adequately dissipated and the removal of chips is adversely affected, which in turn can affect the service life of the tool and the bore quality. The carried out investigations show that the application of CFD simulation is an important research instrument in machining technology and that there is still great potential in the area of tool and process optimization.
The whole world is in a fuel crisis nearly approaching exhaustion, with climate change knocking at our doorsteps. In the fight against global warming, one of the principle components that demands technocratic attention is Transportation, not just as a significant contributor to atmospheric emissions but from a much broader perspective of environmental sustainability.
From the traditional technocratic aspect of transport planning, our epiphany comes in the form of Land Use integrated sustainable transport policy in which Singapore has been a pioneer, and has led the way for both developed and developing nations in terms of mobility management. We intend to investigate Singapore’s Transport policy timeline delving into the past, present and future, with a case by case analysis for varying dimensions in the present scenario through selective benchmarking against contemporary cities like Hong Kong, London and New York. The discussions will include themes of modal split, land use policy, vehicular ownership, emission policy, parking policy, safety and road traffic management to name a few. A visualization of Singapore’s future in transportation particularly from the perspective of automated vehicles in conjunction with last mile solutions is also detailed.
This paper provides a comparative perspective on infrastructure provision in developing Asia's three largest countries: China, India, and Indonesia. It discusses their achievements and shortfalls in providing network infrastructure (energy, transport, water, and telecommunications) over the past two decades. It documents how three quite distinct development paths—and very different levels of national saving and investment—were manifested in different trajectories of infrastructure provision. The paper then describes the institutional, economic, and policy factors that enabled or hindered progress in providing infrastructure. Here, contrasting levels of centralization of planning played a key role, as did countries’ differing abilities to mobilize infrastructure-related revenue streams such as user charges and land value capture. The paper then assesses future challenges for the three countries in providing infrastructure in a more integrated and sustainable way, and links these challenges with the global development agenda to which the three countries have committed. The concluding recommendations hope to provide a platform for further policy and research dialogue.
This study evaluates the influence of quality certificates on sustainable food production in Poland, considering economic, social, and environmental dimensions. Analyzing 25 different certificates, the research explores their criteria, procedures, and costs across various food product categories, including meat, fish, and plant-based products. The study provides a detailed review of certification processes, from initiation to audits and inspections. It identifies both commonalities and differences among certificates, each addressing unique aspects such as environmental impact, worker rights, and product origins. Despite the diversity in standards and procedures, the study underscores the need for standardized international criteria to improve transparency and meet consumer expectations, highlighting the significant role of quality certificates in advancing sustainable food production.
Copyright © by EnPress Publisher. All rights reserved.