Failure mechanisms and cutting characteristics of brazed single diamond grains

The knowledge about the cutting characteristics and the critical loading of brazed diamonds is essential for a safe and economic application of engineered grinding tools. Scratch tests were performed with single grains. The experiments were conducted with standard polyhedral diamond grains of different sizes, ranging from 300 to 850μm, brazed with an Ag-Cu-based and a Cu-Sn-based active filler alloy onto a steel pin. Two failure mechanisms were revealed, namely "grain pullout” and "grain fracture”. Large grits mainly fail by grain fracture, whereas the smaller ones were mostly pulled out. This trend is supported by a simple mechanical model. The critical values, i.e. cutting force/scratch area, for grain fracture and grain pullout show a decrease with bigger grit size. Scratches are also analysed in terms of cutting characteristics. The dependency of the cutting and the normal force on the scratch area can be described by a power law with powers ranging between about 0.2 and 0.7, respectively. The measured cutting forces strongly depend on the rake angle, which was tested for −19.5° and −35.3

Influence of the brazing parameters on microstructure, residual stresses and shear strength of diamond-metal joints

The reliability and integrity of diamond cutting tools depend on the properties of diamond-metal joints as created by a brazing process. Block-shaped monocrystalline diamonds were brazed onto a steel substrate (X2CrNiMo 18-14-3), using silver-copper based Cusil-ABA™ (Ag-35wt%Cu-1.75wt%Ti) filler alloy. The experimental procedure includes a thorough microstructural investigation of the filler alloy, the determination of the induced residual stresses by Raman spectroscopy as well as the joint's shear strength utilizing a special shear device. The brazing processes were carried out at 850, 880 and 910°C for dwell durations of 10 and 30min, respectively. At the steel interface two interlayers develop. The layers grow with extended dwell duration and higher brazing temperature. The residual stresses only slightly depend on the brazing parameters and exhibit a maximum value of −400MPa. Unlike the residual stresses, the shear strength strongly depends on the brazing parameters and thus on the microstructure. Three failure modes could be identified; a ductile fracture in the filler alloy, a brittle fracture in the interlayers and a partly shattering of the diamon

EXC!TE SNARE DRUM — Making an Audio Plugin with Pure Data inside

This report describes how we made a VST3 plugin containing Pure Data and integrated libpd into VCV Rack, iPlug2 and the VST3SDK. The plugin is a real-time snare drum synthesizer using an exciter-resonator model. We discovered an undesirable effect in Pd where the computationally cheap 4-point interpolation on delread4~ creates audible artefacts, effecting our wave-guide. Our solution to this issue was to implement our own interpolation object based on advice from Cyrille Henry posted to the Pd mailing list in 2008. The implementation was taken from Julius O. Smith's Digital Audio Resampling reference book

Innovating for and with your service customers: An assessment of the current practice of collaborative service innovation in Germany

AbstractMethods for managing innovation have been described in academia in many contexts. Service innovation processes pose particular challenges compared to those of product innovation – one of the core reasons being the lack of dedicated R&D structures in service firms or units. Collaborative innovation both with employees and with customers can be an effective means to drive innovation in services. Based on empirical evidence of a study of German innovation managers, this paper discusses findings of service innovation in organizational practice. We review the current extent and future potential of the involvement of employees and customers in the innovation process, as well implications for companies and academia

Dei et Apostolicae Sedis Gratia: Über die Entstehung von Personenherrschaft in den Bistümern Bremen und Verden im frühen Mittelalter und die Rezeption dieser Zeit in liturgischen Schriften des Erzbischofs Christoph von Braunschweig-Lüneburg.

This works focuses on the political history of the bishopries of Bremen and Verden (North-Western Germany) during their first 300 years, beginning as unimportant mission-territories until their establishment as confident territories of the Holy German Empire in the 12th century. The second part is emphasizing on the reflection this time has found in liturgical prints during the reign of Archbishop Christoph of Brunswick, whose reign can be seen as a borderline between catholic middle ages and the beginning reformation

On Iterative Pre‐Compensation of 3D Laser‐Printed Micro‐Optical Components Using Confocal‐Optical Microscopy

State-of-the-art 3D two-photon laser printing systems already use pre-compensation algorithms to reduce systematic deviations between the printed and the targeted structures. Nevertheless, the remaining deviations are often still larger than the uncontrollable or “statistical” deviations. In principle, it is straightforward to correct for systematic deviations by measuring the difference between printed structure and target and by subtracting the difference from the first target to obtain the next-iteration target. However, in reality, one faces several issues such as noise and systematic errors of the characterization measurement itself, as well as unwanted translations and rotations between the coordinate systems of the characterization setup and the printer, respectively. Two examples of printed structures requiring sub-micrometer accuracy are considered, a large 1D micro-lens array and a specific diffractive optical element. For both, the device performance before the pre-compensation workflow described herein is insufficient for the targeted application and has become sufficient after this workflow. The workflow involving optimizations using cross-correlations with confocal-optical-microscopy data is documented by an open-access program (available via GitLab). This program includes an easy-to-use graphical user interface so that other researchers can immediately profit from it

Evolutionary testing supported by slicing and transformation

Evolutionary testing is a search based approach to the automated generation of systematic test data, in which the search is guided by the test data adequacy criterion. Two problems for evolutionary testing are the large size of the search space and structural impediments in the implementation of the program which inhibit the formulation of a suitable fitness function to guide the search. In this paper we claim that slicing can be used to narrow the search space and transformation can be applied to the problem of structural impediments. The paper presents examples of how these two techniques have been successfully employed to make evolutionary testing both more efficient and more effective

Survey about the dissemination of different cabin categories in plant protection of German practice

Das Bundesamt für Verbraucherschutz und Lebensmittelsicherheit (BVL) hat festgelegt, dass bestimmte Fahrerkabinen beim Einsatz im Pflanzenschutz geeignet sind, persönliche Schutzausrüstung zu ersetzen, die mit der Zulassung von Pflanzenschutzmitteln während der Anwendung vorgeschrieben sind. Diese Schutzwirkung wird seit 2017 für Fahrerkabinen der Kategorien 3 oder 4 (EN 15695-1/2017) und seit 2020 für geschlossene Kabinen, die über eine Klimaanlage sowie eine Zuluft-Filterung verfügen (BVL-Kategorie 2*), angenommen. Das Schutzniveau von Kat. 2* Kabinen wird aktuell in einem Forschungsprojekt untersucht.Vor diesem Hintergrund wurde eine Umfrage bei Praktikern durchgeführt, um mehr Informationen über die Verbreitung und Ausstattung von Traktorkabinen in der landwirtschaftlichen Praxis in Deutschland zu erhalten.Der Fragebogen gliedert sich in zwei Abschnitte. Im ersten Teil werden demografische Daten zur Person sowie Daten zur Struktur und Lage des Betriebs erfasst. Im zweiten Teil geht es um die technische Ausstattung und Nutzung der Fahrzeuge. Insgesamt konnten 4.199 gültige Fragebögen ausgewertet werden. Die Ergebnisse aus Teil 1 der Umfrage zur prozentualen Verteilung der beteiligten Betriebe über die Bundesländer und die repräsentierten Betriebsgrößen sind nahe an den statistischen Daten von Destatis. Größere Betriebe sind in dieser Umfrage leicht überrepräsentiert. Trotzdem liefern die Ergebnisse profunde Informationen über die Verbreitung von verschiedenen Kabinenkategorien in der landwirtschaftlichen Praxis im Pflanzenschutz in Deutschland.Die Auswertung zeigt, dass es in den letzten 10 Jahren zu einer signifikanten Zunahme von Kabinen der Kategorie 3 und 4 in der Praxis gekommen ist, mit einem etwas höheren Anteil bei den größeren Betrieben. In Bezug auf die Betriebsform ist der Anteil von Kategorie 3 und 4 Kabinen insbesondere im Obstbau, in den Spezialkulturen und bei den Lohnunternehmen höher. Die Umfrage lieferte weitere Ergebnisse, unabhängig von der Kabinenkategorie. Es zeigte sich, dass das Wechselintervall bei den Zuluft-Filtern in den meisten Fällen kleiner als 2 Jahre ist, dass 40% der Befragten angeben, ihre Kabinen nach der Applikation von Pflanzenschutzmitteln zu reinigen und knapp 90% der Anwender sich in ihrer Kabine gut gegen Pflanzenschutzmittel geschützt fühlen. Die Ergebnisse sind plausibel und decken sich mit früheren Annahmen. Mit der Veröffentlichung der Ergebnisse liegen jetzt stichhaltige Informationen zu diesem Thema vor.The Federal Office of Consumer Protection and Food Safety (BVL) specified that certain driver cabs are suitable to replace personal protective equipment prescribed with the approval of plant protection products during application. This protective effect has been accepted since 2017 for category 3 or 4 driver's cabs (EN 15695-1/2017) and since 2020 for enclosed cabs equipped with air conditioning including an air filtration system (BVL category 2*). The protection level of cat. 2* cabins is currently being investigated in a research project. In this context, a survey of farmers was conducted to obtain more information about the distribution and equipment of tractor cabins in agricultural practice in Germany. The questionnaire is divided into two sections. The first part collects personal demographic data and data on the structure and location of the farms. The second part deals with the technical equipment and use of the vehicles. A total of 4,199 valid questionnaires were evaluated. The results from Part 1 of the survey on the percentage distribution of participating farms across the German Federal States and the sizes of farms represented are close to the statistical data from Destatis. Larger farms are slightly overrepresented in this survey. Nevertheless, the results provide profound information on the prevalence of different cab categories in agricultural practice in plant protection in Germany.The survey provided further results, regardless of the cab category. It showed that the replacement interval for cabin air filters is less than 2 years in most cases, that 40% of the participants indicated that they clean their cab after applying plant protection products, and that almost 90% of the users feel well protected against plant protection products in their cab. The results are plausible and in line with earlier assumptions. With the publication of the results, valid information on this topic is now available