Cumulative index to NASA Tech Briefs, 1970-1975

Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented

An investigation into heat dissipation from a stationary commercial vehicle disc brake in parked conditions.

Detailed understanding of heat dissipation from a stationary disc brake is of considerable importance for vehicle safety. This is essential for both park braking on inclines and for preventing brake fluid boiling in hydraulic brakes. Despite the experience proving the significance of such conditions, there is very little published data dealing with this phenomenon, and even ECE Regulation 13 does not specify hot parking braking performance. The problem of heat dissipation from stationary brake may appear simplistic but it is actually more complex than from a rotating disc, due to the lack of symmetry through or a dominant mode of heat transfer as natural convection is the only driving force behind the airflow. All three heat transfer modes exist in a transient process, with complex heat transfer paths within and between brake components. This Thesis investigates the cooling performance of a Commercial Vehicle (CV) brake whilst in stationary conditions. The research is predominantly orientated towards the thermal aspects of Electric Parking Brake (EPB) application in CVs. Contraction of large brake components after hot parking may lead to vehicle rollaway on inclines, with tragic consequences. An extensive theoretical and experimental study was conducted. An analytical model of a disc brake in free air was developed, enabling good prediction of disc temperatures and average surface convective heat transfer coefficients (hcₒnv) over the entire cooling range. A comprehensive CFD modelling of the 3-dimensional flowfield around the disc brake was also conducted, as well as predicting the surface convection coefficient distribution. Shear Stress Turbulence model was found to be most suitable for such studies. FE models were created to predict temperatures in all components of the brake assembly. A special Thermal Rig was developed for experimental validations, which uses an induction heater for heating the disc brake, and numerous surface mounted and embedded thermocouples for measuring component temperatures, as well as ‘free standing’ for determining air temperatures in specific points. IR cameras provided further temperature field information. The results clearly show little influence of the conductive heat dissipation mode. The study also showed, for the experimental arrangement used, a constant value of surface emissivity (ɛ = 0.92). With well-defined conductive and radiative heat dissipation modes, the emphasis was placed on investigating convective heat dissipation from a stationary disc brake. It has been demonstrated that the anti-coning straight vane design of brake disc does not cool effectively in stationary conditions. Expected ‘chimney effects’ in disc vent channels do not materialise due to large scale recirculation regions preventing airflow from entering the channels, which drastically reduces the convective cooling. Complex thermal interactions between the large assembly components are explained, with typical cooling time being just over an hour for disc brake cooling from 400°C to 100°C. Extracted heat transfer coefficients were used for establishing a complex FE assembly model, which enables accurate prediction of temperatures of individual components over the entire cooling period. The developed approach is used for predicting temperature of the existing brake assembly but is equally suited for generating new designs with more favourable characteristics. In addition to being a powerful design tool for assisting in EPB design and validation process, the methodology developed offers wide applications, such as thermal optimisation of the caliper housing for the installation of continuous wear monitoring sensors, smart slack adjusters (for low friction drag brakes), etc. EPBs in passenger cars have been successfully used for over 10 years now. They use a relatively simple approach for ensuring safe parking from hot by over-clamping (applying approximately twice the required actuating force) and re-clamping (repeated application after the vehicle has been parked). Large CV actuating forces prevent the use of over-clamping as this could damage the disc, whilst re-clamping would need to be repeated several times over a much longer period of time, requiring the vehicle battery to power the electronic systems for a longer period of time without recharging. Neither approach is acceptable, requiring a more in- depth thermal study of the CV brake in stationary conditions, as investigated in this Thesis. In addition to technical, there are marketing and financial aspects which make EPB introduction and acceptance in commercial vehicles very different to passenger car applications. Such an investigation was conducted, exploring the market the CV EPB will be sold in and whether it would accept the new technology. Two questionnaire analyses were carried out, with the second giving the respondent detailed information about the EPB. It was found that using an informed, knowledge based approach yielded more positive feedback to the proposed product. The outcome may be even considered more contrary than expected, rather than instigating mistrust, the new CV EPB technology created interest. Furthermore, reports of pneumatic malfunction indicated that independence from the pneumatic system should be used as the key selling point for the EPB, for all beneficiary segments.Engineering and Physical Sciences (EPSRC)Eng

Time Localization of Abrupt Changes in Cutting Process using Hilbert Huang Transform

Cutting process is extremely dynamical process influenced by different phenomena such as chip formation, dynamical responses and condition of machining system elements. Different phenomena in cutting zone have signatures in different frequency bands in signal acquired during process monitoring. The time localization of signal’s frequency content is very important. An emerging technique for simultaneous analysis of the signal in time and frequency domain that can be used for time localization of frequency is Hilbert Huang Transform (HHT). It is based on empirical mode decomposition (EMD) of the signal into intrinsic mode functions (IMFs) as simple oscillatory modes. IMFs obtained using EMD can be processed using Hilbert Transform and instantaneous frequency of the signal can be computed. This paper gives a methodology for time localization of cutting process stop during intermittent turning. Cutting process stop leads to abrupt changes in acquired signal correlated to certain frequency band. The frequency band related to abrupt changes is localized in time using HHT. The potentials and limitations of HHT application in machining process monitoring are shown

Advances in raw material industries for sustainable development goals

"""Advances in Raw Material Industries for Sustainable Development Goals"" presents the results of joint scientific research conducted in the context of the Russian-German Raw Materials Forum. Today Russia and Germany are exploring various forms of cooperation in the field of mining, geology, mineralogy, mechanical engineering and energy. Russia and Germany are equally interested in expanding cooperation and modernizing the economy in terms of sustainable development. The main theme of this article collection is connected with existing business ventures and ideas from both Russia and Germany. In this book the authors regard complex processes in mining industry from various points of view, including: - modern technologies in prospecting, exploration and development of mineral resources - progressive methods of natural and industrial mineral raw materials processing - energy technologies and digital technologies for sustainable development - cutting-edge technologies and innovations in the oil and gas industry. Working with young researchers, supporting their individual professional development and creating conditions for their mobility and scientific cooperation are essential parts of Russian-German Raw Materials Forum founded in Dresden 13 years ago. This collection represents both willingness of young researchers to be involved in large-scale international projects like Russian-German Raw Material Forum and the results of their long and thorough work in the promising areas of cooperation between Russia and Germany.

Proceedings of the West Africa Built Environment Research (WABER) Conference 2021

FOREWORD: I would like to welcome each participant to the WABER 2021 Conference. Since its inception in 2009, the WABER Conference series has done a great deal to nurture and support researchers, initially in West Africa, also, in other parts of Africa and elsewhere. I would like to thank all delegates for your participation which enables us to keep this Conference going. The WABER Conference enjoys a positive international reputation and has continued to grow from strength to strength over the past 13 years. For this, I would like to thank our team, keynote speakers and participants over the years for every contribution you have made to the success of this Conference. This year's Conference has an excellent programme, line up of speakers and authors. I would like to thank and commend the authors of all 72 papers in this Conference proceedings. If the research paper writing process was compared to a marathon, the authors of the 72 papers in this publication would be adjudged as the ones who have endured and finished the race. We opened the call for papers for this Conference in December 2020 and over 100 abstracts were submitted by authors. However, it is one thing to propose to write a paper, and it is quite another thing to actually write the paper. Therefore, I would like to thank and congratulate all authors who succeeded in completing the process of getting published in this conference proceedings. It is befitting that we have an excellent range of interesting topics in the 72 papers to be discussed at this conference. We are honoured to welcome Professor Charles Egbu, Vice Chancellor of Leeds Trinity University, to give us a special opening address. In the three days of this conference, we will have various plenary presentations by experienced international academics and I would like to thank and welcome each of them below. Professor Albert Chan Richard Lorch Professor Taibat Lawanson Professor Dato’ Sri Ar Dr Asiah Abdul Rahim Professor George Ofori. In addition to these speakers, we have other interesting sessions on the programme including a special session for doctoral students and supervisors several other experienced speakers addressing various topics that should be of interest to many of us. I would like to thank all members of the organising team particularly Associate Professor Emmanuel Essah, Dr Yakubu Aminu Dodo and Dr Sam Moveh for their efforts which has helped to organise this Conference successfully. I would also like to thank all of our reviewers particularly Associate Professor Emmanuel Essah and Dr Haruna Moda for the considerable time and effort spent reviewing and checking all papers to ensure a high standard of quality. The WABER Conference Team always plays an excellent role in the success of our events and I would like to thank and appreciate the contributions of Florence, Sam Boakye, Victor Ayitey and his team, Kwesi Kwofie and Issah Abdul Rahman to the success of this Conference. I hope you enjoy our first hybrid conference and engage with our exciting speakers on the diverse topics that will be covered over the three days of this Conference

Standard Specifications for Road and Bridge Construction, January 1, 2021

https://digitalcommons.memphis.edu/govpubs-tn-dept-transportation-standard-specifications/1000/thumbnail.jp