Sensitive gravity-gradiometry with atom interferometry: progress towards an improved determination of the gravitational constant

We here present a high sensitivity gravity-gradiometer based on atom interferometry. In our apparatus, two clouds of laser-cooled rubidium atoms are launched in fountain configuration and interrogated by a Raman interferometry sequence to probe the gradient of gravity field. We recently implemented a high-flux atomic source and a newly designed Raman lasers system in the instrument set-up. We discuss the applications towards a precise determination of the Newtonian gravitational constant G. The long-term stability of the instrument and the signal-to-noise ratio demonstrated here open interesting perspectives for pushing the measurement precision below the 100 ppm level

The Uncertainty in Newton's Constant and Precision Predictions of the Primordial Helium Abundance

The current uncertainty in Newton's constant, G_N, is of the order of 0.15%. For values of the baryon to photon ratio consistent with both cosmic microwave background observations and the primordial deuterium abundance, this uncertainty in G_N corresponds to an uncertainty in the primordial 4He mass fraction, Y_P, of +-1.3 x 10^{-4}. This uncertainty in Y_P is comparable to the effect from the current uncertainty in the neutron lifetime, which is often treated as the dominant uncertainty in calculations of Y_P. Recent measurements of G_N seem to be converging within a smaller range; a reduction in the estimated error on G_N by a factor of 10 would essentially eliminate it as a source of uncertainty in the calculation of the primordial 4He abundance.Comment: 3 pages, no figures, fixed typos, to appear in Phys. Rev.

5D gravity and the discrepant G measurements

It is shown that 5D Kaluza-Klein theory stabilized by an external bulk scalar field may solve the discrepant laboratory G measurements. This is achieved by an effective coupling between gravitation and the geomagnetic field. Experimental considerations are also addressed.Comment: 13 pages, to be published in: Proceedings of the 18th Course of the School on Cosmology and Gravitation: The gravitational Constant. Generalized gravitational theories and experiments (30 April-10 May 2003, Erice). Ed. by G. T. Gillies, V. N. Melnikov and V. de Sabbata, (Kluwer), 13pp. (in print) (2003

Maximizing benefits : the redesign of MYTERIAL's supplier routing algorithm

To ensure a better customer experience, the construction tech startup MYTERIAL is facing a series of internal changes. One of the changes foresees the redesign of the currently used supplier routing algorithm (SRA). However, to elaborate this, MYTERIAL cannot rely on internal specifications only, but must also include use cases from external construction companies. Based on different perspectives of several management methods, this study discusses various possibilities of redesigning the currently used SRA. Hence, semi-structured user interviews as well as expert interviews were conducted to detect current challenges and to determine external use cases and missing features. Resulting from this, eligible features were built into two scenarios, showing how the future SRA could look like. In a follow-up discussion, the advantages and disadvantages of both scenarios were contrasted. It was determined that construction companies can benefit from a realigned SRA in several aspects. This can be accomplished by involving the customer himself more in the design of his own, individual SRA.Para garantir uma melhor experiência para o cliente, a startup de tecnologia de construção MYTERIAL está a implementar uma série de mudanças internas. Uma das mudanças prevê a redesenho do algoritmo de roteamento de fornecedores (SRA) atualmente em uso. No entanto, para o fazer, a MYTERIAL não pode depender apenas de especificações internas, mas também deve incluir casos de uso de empresas externas de construção. Considerando diferentes perspectivas de vários métodos de gestão, este estudo discute várias possibilidades de redesenho do SRA atualmente utilizado. Com este objectivo em mente, foram realizadas entrevistas com utilizadores e consultas com especialistas para identificar os desafios atuais e determinar casos de uso externos e recursos ausentes. Com estes resultados, recursos elegíveis foram incorporados em dois cenários, mostrando possíveis futuros do SRA. Numa análise posterior, foram contrastadas as vantagens e desvantagens de ambos os cenários. Verificou-se que empresas de construção podem beneficiar de um SRA realinhado em vários aspectos. Isso pode ser alcançado envolvendo o próprio cliente de forma mais profunda no design do seu próprio SRA individual

Bearbeitungspotentiale durch werkstoffgereche Prozeßführung

Die Werkstofftechnologie ermöglicht heute die Konstruktion von Bauteilen mit herausragenden Eigenschaften. Geringer Verschleiß und hohe Festigkeit beim Einsatz in aggressiven Medien oder unter hohen Temperaturen oder überragende Festigkeit bei niedrigem Gewicht sind einige bespielhafte Kennzeichen dieser Materialien. Die praktische Ausnutzung dieser Eigenschaften erfordert allerdings eine Bearbeitung, welche die werkstoffspezifischen Vorzüge erhält und gleichzeitig wirtschaftlich ist. Die werkstoffgerechte Schleifbearbeitung von Hochleistungskeramiken und optischen Gläsern sowie das Fräsen von faserverstärkten Thermoplasten stehen als Beispiele für die gelungene Anpassung spanender Fertigungsverfahren an die speziellen Erfordernisse des Werkstoffs. Die Entwicklung neuartiger Fertigungsverfahren stellt ebenfalls einen Schritt zur materialgerechten Bearbeitung dar. Das laserunterstützte Drehen ist ein Verfahren, das für die Bearbeitung hochwarmfester Materialien aufgrund seiner hohen Fle xibilität interessante Anwendungsperspektiven eröffnet