Increasing the safety against scuffing of additive manufactured gear wheels by internal cooling channels

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)The layer-by-layer principle of the additive manufacturing (AM) technology of Laser-Powder-Bed-Fusion (LPBF) creates new opportunities in the design and manufacturing of efficient gear components. For example, integrating a cooling system can increase the safety against scuffing or reduce the amount of required lubrication and thus the splashing losses. Quenched and tempered steels or case-hardened steels are commonly used in the fabrication of gear components. However, the availability of these alloys for LPBF processing is still limited. The development of suitable LPBF metal gears (with a Gear Research Centre (FZG) type A geometry) out of quenched and tempered 30CrNiMo8 steel with internal cooling channels shows the possibility of significantly increasing the safety factor against scuffing. This work includes the development of a suitable cooling strategy, material development, the setup of a suitable test infrastructure and the analysis of the LPBF gears tested for scuffing

Inter-Particle Distribution Functions for One-Species Diffusion-Limited Annihilation, A+A->0

Diffusion-limited annihilation, $A+A\to 0$, and coalescence, $A+A\to A$, may both be exactly analyzed in one dimension. While the concentrations of $A$ particles in the two processes bear a simple relation, the inter-particle distribution functions (IPDF) exhibit remarkable differences. However, the IPDF is known exactly only for the coalescence process. We obtain the IPDF for the annihilation process, based on the Glauber spin approach and assuming that the IPDF's of nearest-particle pairs are statistically independent. This assumption is supported by computer simulations. Our analysis sheds further light on the relationship between the annihilation and the coalescence models.Comment: 15 pages, plain TeX, 3 figures - available upon request (snail mail

Aging in Models of Non-linear Diffusion

We show that for a family of problems described by non-linear diffusion equations an exact calculation of the two time correlation function gives C(t,t')=f(t-t')g(t'), t>t', exhibiting normal and anomalous diffusions, as well as aging effects, depending on the degree of non-linearity. We discuss also the form in which FDT is violated in this class of systems. Finally we argue that in this type of models aging may be consequence of the non conservation of the "total mass".Comment: 4 pages, 1 figure, to appear in Phys.Rev.

Introducing a nationwide registry: the Swiss study on aneurysmal subarachnoid haemorrhage (Swiss SOS)

Background: Aneurysmal subarachnoid haemorrhage (aSAH) is a haemorrhagic form of stroke and occurs in a younger population compared with ischaemic stroke or intracerebral haemorrhage. It accounts for a large proportion of productive life-years lost to stroke. Its surgical and medical treatment represents a multidisciplinary effort. Due to the complexity of the disease, the management remains difficult to standardise and quality of care is accordingly difficult to assess. Objective: To create a registry to assess management parameters of patients treated for aSAH in Switzerland. Methods: A cohort study was initiated with the aim to record characteristics of patients admitted with aSAH, starting January 1st 2009. Ethical committee approval was obtained or is pending from the institutional review boards of all centres. In the study period, seven Swiss hospitals (five university [U], two non-university medical centres) harbouring a neurosurgery department, an intensive care unit and an interventional neuroradiology team so far agreed to participate in the registry (Aarau, Basel [U], Bern [U], Geneva [U], Lausanne [U], St. Gallen, Zürich [U]). Demographic and clinical parameters are entered into a common database. Discussion: This database will soon provide (1) a nationwide assessment of the current standard of care and (2) the outcomes for patients suffering from aSAH in Switzerland. Based on data from this registry, we can conduct cohort comparisons or design diagnostic or therapeutic studies on a national level. Moreover, a standardised registration system will allow healthcare providers to assess the quality of car

Case Report: Emergency awake craniotomy for cerebral abscess in a patient with unrepaired cyanotic congenital heart disease [version 1; referees: 2 approved]

We report the case of a 39-year-old male with complex cyanotic congenital heart disease undergoing emergency craniotomy for a cerebral abscess. Maintenance of intraoperative hemodynamic stability and adequate tissue oxygenation during anesthesia may be challenging in patients with cyanotic congenital heart disease. In this case, we decided to perform the surgery as an awake craniotomy after interdisciplinary consensus. We discuss general aspects of anesthetic management during awake craniotomy and specific concerns in the perioperative care of patients with congenital heart disease

Case Report: Emergency awake craniotomy for cerebral abscess in a patient with unrepaired cyanotic congenital heart disease [version 2; referees: 2 approved]

We report the case of a 39-year-old male with complex cyanotic congenital heart disease undergoing emergency craniotomy for a cerebral abscess. Maintenance of intraoperative hemodynamic stability and adequate tissue oxygenation during anesthesia may be challenging in patients with cyanotic congenital heart disease. In this case, we decided to perform the surgery as an awake craniotomy after interdisciplinary consensus. We discuss general aspects of anesthetic management during awake craniotomy and specific concerns in the perioperative care of patients with congenital heart disease

Function- and weight-optimized gear components by Laser Powder Bed Fusion (L-PBF)

Drive systems have to be designed ever lighter and more efficient. Smaller mass moments of inertia and optimized design for cooling, lubrication, and tooth engagement can significantly increase the efficiency of gears. Additively manufactured gears components made of typical gear steels such as steel for quenching and tempering e.g. 30CrNiMo8 offer great potential in this respect. This project combines knowledge in the field of gear design and additive manufacturing technology (Laser Powder Bed Fusion L-PBF)

Funktions-und gewichtsoptimierte Zahnräder : additiv durch selektives Laserschmelzen hergestellt

Antriebssysteme müssen immer leichter und effizienter gestaltet werden. Kleinere Massenträgheitsmomente und optimierte Gestaltung für Kühlung, Schmierung und Zahneingriff können die Effizienz von Getriebe merklich erhöhen. Im SLM-Verfahren hergestellte Zahnräder mit typischen Getriebestählen wie beispielsweise dem 30CrNiMo8 bieten dabei grosses Potenzial. Der Vortrag zeigt, wie das Wissen im Bereich Zahnraddesign und des SLM-Verfahrens erfolgreich kombiniert werden