The thermal conductivity of cortical and cancellous bone

Surgical interventions close to vulnerable structures, such as nerves, require precise handling of surgical instruments and tools. These tools not only pose the risk of mechanical damage to soft tissues, but they also generate heat, which can lead to thermal necrosis of bone or soft tissues. Researchers and engineers are trying to improve those tools through experimentation and simulations. To simulate temperature distributions in anatomical structures, reliable material constants are needed. Therefore, this study aimed at investigating the thermal conductivity of cortical and cancellous bone. Accordingly, a custom-made steady-state experimental setup was designed and validated. 6 bovine and 3 human cortical bone samples, as well as 32 bovine cancellous bone samples, with variable bone volume fraction were tested. The cancellous bone samples were scanned by micro-computed tomography (µCT) and micro-finite element (µFE) voxel models were created to calculate iteratively the thermal conductivity of the bone marrow. The experimental results provided 0.64 ± 0.04 W/mK for bovine cortical bone and 0.68 ± 0.01 W/mK for human cortical bone. A linear dependency of thermal conductivity on bone volume fraction was found for cancellous bone [R-square (R2) = 0.8096, standard error of the estimates (SEE) = 0.0355 W/mK]. The thermal conductivity of the bone marrow was estimated to be 0.42 ± 0.05 W/mK. These results will help to improve thermal finite element simulations of the human skeleton and aid the development of new surgical tools or procedures

Validation of Procedures for Market Screening of Non-Road Machines

For the precedent project “In-Service Monitoring of Non-Road Mobile Machinery”, supplementary activities in the given project have been performed. The aim of the present project was to give an extended validation of the proposed procedure for market screening of non-road machines. The same machine and agricultural processes were transferred from the field application into a re-producible test bench, for the validation of the process without environmental influence. The present report demonstrates the reproducibility of the agricultural cycles and maneuvers on the test bench. The reliability on results of field and test bench measurements were discussed from the point of emission standards. The same tractor, as in the former project, was used to avoid differences in the results due to manufacturing. The important conclusions are: For the cycles: • Measured cycles from the field test can be transferred very well. When sufficient data is recorded. • For the used tractor class, the DLG standard cycles are representative and comparable with the field measurements. • Other agricultural machines of a different type and performance class should be examined to see whether the cycles are also representative here. For the tractor: • Heating the exhaust gas after treatment in idle is not to recommended. • The powertrain of the tractor allows to maintain engine speed in a constant range, even when tractor velocity changes. • When performing tasks under full load the tractor has very low emissions • Implemented right, the OBD signals are sufficient to obtain the performed work of the engine For the procedure: • Cycles measured in the field can be transferred effortless • The deviation in results between field and dynamometer are small • The “DLG” standard cycles represent the intend task very well. • The performed cycles on dynamometer are reproducible as expected. Further research topics are proposed. Some of them are: • Testing other tractor applications for statistical hedging. • Extension of this research field to other types of machines and processes. • Further analysis for a universal load-speed cycle for PTI procedures. • Contacts and exchange of experiences with JRC ERMES, with other research institutes and with manufacturers

Einfluss der Leistungssteigerung auf die Emissionen bei landwirtschaftlichen Fahrzeugen

Im vorliegenden Bericht werden die Einflüsse der heutigen Leistungssteigerungsmöglichkeiten auf die Emissionen von landwirtschaftlichen Fahrzeugen dargestellt. Hierzu wurde ein Traktor mit zwei handelsüblichen Tuning-Sets ausgestattet. Leistungs- und Emissionsverhalten des Traktors wurden in einem ersten Schritt im Originalzustand, mit den beiden Tuning Sets sowie mit einer Abschaltvorrichtung für das SCR-System stationär an der Zapfwellenbremse vermessen. Anschließend wurde der Traktor im Originalzustand sowie mit den beiden Tuning-Varianten für Transport- und Feldarbeiten eingesetzt, dabei wurden die Emissionen mittels PEMS gemessen, um einen allfälligen Effekt auf die Emissionen nachzuweisen. Die Tuning-Sets führten zu Mehrleistungen von rund 20%. Ebenfalls wurde das Fahrzeug mit abgeschalteter SCR Vorrichtung, ohne weitere Probleme (z.B. Aktivierung des Notlaufprogramms) in Betrieb genommen. Emissionen, insbesondere die NOx Werte lagen auf vergleichbaren Niveau gegenüber der Variante ohne Tuning. Vergleichbar fiel das Verhalten des Kraftstoffverbrauches aus, bis auf eine Messung konnte keine wesentliche Steigerung gegenüber dem Serienstand festgestellt werden

Market Surveillance Concept for Non-Road Mobile Machinery

This project carried out by BFH-TI and BFH-HAFL contributes to the field of in-service monitoring (ISM) as required for non-road mobile machinery (NRMM) according to Regulation (EU) 2016/1628 (Stage V). Based on the 2018 pilot project, additional field studies were conducted, but with another test tractor. The aim was to further investigate and improve the practical implementation of ISM. Various field tasks were chosen to cover a broad spectrum of load and dynamic cases for the engine and exhaust aftertreatment system. The possibilities to simplify the practical process of ISM were also investigated and presented. In addition, various workshops were planned and conducted with the Swiss Federal Office for the Environment (FOEN) on the subject of ISM, considering not only technical but also legal aspects. A further component of the project was the exchange of information with other experts in the field of emission measurement in NRMM and other stakeholders on the topic of ISM. The views and additional perspectives on ISM of experts and stakeholders are also presented