2,257 research outputs found
Dynamic Parameter Allocation in Parameter Servers
To keep up with increasing dataset sizes and model complexity, distributed
training has become a necessity for large machine learning tasks. Parameter
servers ease the implementation of distributed parameter management---a key
concern in distributed training---, but can induce severe communication
overhead. To reduce communication overhead, distributed machine learning
algorithms use techniques to increase parameter access locality (PAL),
achieving up to linear speed-ups. We found that existing parameter servers
provide only limited support for PAL techniques, however, and therefore prevent
efficient training. In this paper, we explore whether and to what extent PAL
techniques can be supported, and whether such support is beneficial. We propose
to integrate dynamic parameter allocation into parameter servers, describe an
efficient implementation of such a parameter server called Lapse, and
experimentally compare its performance to existing parameter servers across a
number of machine learning tasks. We found that Lapse provides near-linear
scaling and can be orders of magnitude faster than existing parameter servers
Up and down scale considerations for the continuous production of glycooptimized biopharmaceuticals
Product quality especially with respect to glycosylation is a critical product attribute which can have an immense influence on the activity of glycoproteins and should be closely monitored during process development and manufacturing. GlycoExpressTM cells have been developed in this context to provide human host cell lines with robust glycosylation machineries. This work will address challenges in two case studies for up and down scaling of production processes with focus on product quality and continuous processing. In a first section, data of a process transfer from a 200 L stainless steel to a 1000 L single-use bioreactor for a continuous cell culture application is discussed. The impact of engineering aspects for the bioreactor and the cell retention device as well as product quality considerations are addressed. As a second part, a 10 mL down-scale system for perfusion cultivations in a microbioreactor is introduced and its application for process development is evaluated. A GlycoExpress-based Phase II GMP perfusion process for mAb production at the 200 L stainless steel scale was successfully transferred to a 1000 L single-use bioreactor. Growth, productivity and stable glycosylation were maintained during scale up. The developed perfusion down-scale system SAM shows very good comparability to larger scale ATF runs not only for USP characteristics but also for product quality. The system predicts the response to media supplementation better than batch or chemostat approaches. Design of Experiment studies can be easily performed with this system resulting in highly significant model
Mechanochemical Synthesis of Cu2MgSn3S8 and Ag2MgSn3S8
Two new thiospinels of the type AI2BIICIV3SVI8 were successfully synthesized via a mechanochemical route using binary sulfides and sulfur. Cu2MgSn3S8 and Ag2MgSn3S8 are the first AI2BIICIV3SVI8 compounds with magnesium as divalent cation. The crystal structures of Cu2MgSn3S8 and Ag2MgSn3S8 were refined in the cubic space group Fd3m using X‐ray powder diffraction. According to UV/Vis measurements, a direct optical bandgap of ca. 1.65 eV was determined for both Cu2MgSn3S8 and Ag2MgSn3S8. Temperature‐dependent magnetic susceptibility measurements of the Cu2MgSn3S8 sample indicate diamagnetism. A 119Sn Mössbauer spectrum confirms the tetravalent state of tin, underlining the electron‐precise description.TU Berlin, Open-Access-Mittel - 202
Secure Communication Using Electronic Identity Cards for Voice over IP Communication, Home Energy Management, and eMobility
Using communication services is a common part of everyday life in a personal
or business context. Communication services include Internet services like
voice services, chat service, and web 2.0 technologies (wikis, blogs, etc), but
other usage areas like home energy management and eMobility are will be
increasingly tackled. Such communication services typically authenticate
participants. For this identities of some kind are used to identify the
communication peer to the user of a service or to the service itself. Calling
line identification used in the Session Initiation Protocol (SIP) used for
Voice over IP (VoIP) is just one example. Authentication and identification of
eCar users for accounting during charging of the eCar is another example. Also,
further mechanisms rely on identities, e.g., whitelists defining allowed
communication peers. Trusted identities prevent identity spoofing, hence are a
basic building block for the protection of communication. However, providing
trusted identities in a practical way is still a difficult problem and too
often application specific identities are used, making identity handling a
hassle. Nowadays, many countries introduced electronic identity cards, e.g.,
the German "Elektronischer Personalausweis" (ePA). As many German citizens will
possess an ePA soon, it can be used as security token to provide trusted
identities. Especially new usage areas (like eMobility) should from the start
be based on the ubiquitous availability of trusted identities. This paper
describes how identity cards can be integrated within three domains: home
energy management, vehicle-2-grid communication, and SIP-based voice over IP
telephony. In all three domains, identity cards are used to reliably identify
users and authenticate participants. As an example for an electronic identity
card, this paper focuses on the German ePA
Shrinkage Characteristics of Boulder Marl as Sustainable Mineral Liner Material for Landfill Capping Systems
The soil shrinkage behavior of mineral substrates needs to be considered for engineering long-term durable mineral liners of landfill capping systems. For this purpose, a novel three-dimensional laser scanning device was coupled with (a) a mathematical-empirical model and (b) in-situ tensiometer measurements as a combined approach to simultaneously determine the shrinkage behavior of a boulder marl, installed as top and bottom liner material at the Rastorf landfill (Northern Germany). The shrinkage behavior, intensity, and geometry were determined during a drying experiment with undisturbed soil cores (100 cm 3 ) from two soil pits; the actual in-situ shrinkage was also determined in 0.2, 0.5, 0.8, and 1.0 m depth by pressure transducer tensiometer measurements during a four-year period. The volume shrinkage index was used to describe the pore size dependent shrinkage tendency and it was classified as low (4.9%) for the bottom liner. The in-situ matric potentials in the bottom liner ranged between −100 and −150 hPa, even during drier periods, thus, the previously highest observed drying range (pre-shrinkage stress) with values below −500 hPa and −1000 hPa was not exceeded. Therefore, the hydraulic stability of the bottom liner was given
Approaches to investigate the crack formation of mineral landfill liner systems
The municipal landfill in Rastorf (Schleswig-Holstein) is covered with a temporary till based capping system. Investigations of structural changes (water conductivity, pore function, shrinkage behaviour) were carried out with undisturbed soil cores and two- and three-dimensional measurement techniques.
The usage of different techniques to evaluate the soil volume changes resulted in variations of the available water capacity (ver>ver+hor>3D) and the unsaturated hydraulic conductivity.
In summary, a critical matric potential between -500 and -1000 hPa in conjunction with a low shrinkage tendency (Vs < 5 %) could be seen as main argument for the utilization of till as sealing substrate
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