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Haslak T.,Hof University of Applied Sciences
SACI 2016 - 11th IEEE International Symposium on Applied Computational Intelligence and Informatics, Proceedings | Year: 2016

In the paradigm of the conventional power grid, balance is achieved by matching generated electricity to the arbitrarily changing consumer side. This objective is harder to achieve when renewable energies introduce volatility. We address this issue by introducing controllable loads. In the project a generalized method of description was identified. The findings were applied to a sewage treatment plant. The facility is rescheduled to maximize own consumption from solar generation aiming for grid parity. © 2016 IEEE.


Holzschuher F.,Hof University of Applied Sciences | Peinl R.,Hof University of Applied Sciences
Journal of Computer and System Sciences | Year: 2016

NoSQL and especially graph databases are constantly gaining popularity among developers as they promise to deliver superior performance when handling highly interconnected data compared to relational databases. Apache Shindig is the reference implementation for OpenSocial with a highly interconnected data model. However, it had a relational database as back-end. In this paper we describe our experiences with the graph database Neo4j as back-end and compare Cypher, Gremlin and Java as alternatives for querying data with MySQL. We consider performance as well as usability from a developer's perspective. Our results show that Cypher is a good query language in terms of code readability and has a moderate overhead for most queries (20-200%). However, it has to be supplemented with "stored procedures" to make up for some performance deficits in pattern matching queries (>1000%). The RESTful API is unusable slow, whereas our WebSocket connection performs significantly better (>650%). © 2015 Elsevier Inc. All rights reserved.


Peinl R.,Hof University of Applied Sciences | Holzschuher F.,Hof University of Applied Sciences
CLOSER 2015 - 5th International Conference on Cloud Computing and Services Science, Proceedings | Year: 2015

Docker provides a good basis to run composite applications in the cloud, especially if those are not cloudaware, or cloud-native. However, Docker concentrates on managing containers on one host, but SaaS providers need a container management solution for multiple hosts. Therefore, a number of tools emerged that claim to solve the problem. This paper classifies the solutions, maps them to requirements from a case study and identifies gaps and integration requirements. We conclude that the Docker ecosystem could help moving from IaaS and PaaS solutions towards a runtime environment for SaaS applications, but needs consolidation.


Lawall A.,Hof University of Applied Sciences
Communications in Computer and Information Science | Year: 2016

In all organizations, access assignments are essential in order to ensure data privacy, permission levels and the correct assignment of tasks. Traditionally, such assignments are based on total enumeration, with the consequence that constant effort has to be put into maintaining the assignments. This problem still persists when using abstraction layers, such as group and role concepts, e.g. Access Control Matrix and Role-Based Access Control. Role and group memberships are statically defined and members have to be added and removed constantly. This paper describes a novel approach – Hypergraph-Based Access Control HGAC – to assign human and automatic subjects to access rights in a declarative manner. The approach is based on an organizational metamodel and a declarative language. The language is used to express queries and formulate predicates. Queries define sets of subjects based on their properties and their position in the organizational model. They also contain additional information that causes organization-specific and userdefined relations to be active or inactive depending on predicates. In HGAC, the subjects that have a specific permission are determined by such a query. The query itself is not defined statically but created by traversing a hypergraph path. This allows a structured aggregation of permissions on resources. Consequently, multiple resources can share parts of their queries. © Springer International Publishing Switzerland 2016.


Niemann R.,Hof University of Applied Sciences
ICPE 2016 Companion - Companion Publication for 7th ACM/SPEC International Conference on Performance Engineering | Year: 2016

The ability to accurately simulate and predict the metrics (e.g. performance and energy consumption) of data management systems offers several benefits. It can save investments in both time and hardware. A prominent example is the resource planning. Given a specific use case, a datacenter operator is able to find the most performant or most energy efficient configuration without performing benchmarks or aquiring the necessary hardware. Another possibility would be to study the effects of architectural changes without having them implemented. In this paper, Queued Petri Nets were used to predict and to study the performance and energy consumption of a distributed data management system like Cassandra. The prediction accuracy was evaluated and compared to actual experimental results. On average, the predicted and experimental results differ only by 8 percent for the performance and 16 percent for the energy efficiency, respectively. In addition to this, the experimental results of the used Cassandra cluster revealed a super-linear behavior for the performance and a sub-linear one for the energy consumption. © 2016 ACM.


Lawall A.,Hof University of Applied Sciences
DATA 2015 - 4th International Conference on Data Management Technologies and Applications, Proceedings | Year: 2015

In all organizations, access assignments are essential in order to ensure data privacy, permission levels and the correct assignment of tasks. Traditionally, such assignments are based on total enumeration, with the consequence that constant effort has to be put into maintaining the assignments. This problem still persists when using abstraction layers, such as group and role concepts, e.g. Access Control Matrix and Role-Based Access Control. Role and group memberships are statically defined and members have to be added and removed constantly. This paper describes a novel approach - Hypergraph-Based Access Control H GAC- to assign human and automatic subjects to access rights in a declarative manner. The approach is based on an organizational (meta-) model and a declarative language. The language is used to express queries and formulate predicates. Queries define sets of subjects based on their properties and their position in the organizational model. They also contain additional information that causes organizational relations to be active or inactive depending on predicates. In H GAC, the subjects that have a specific permission are determined by such a query. The query itself is not defined statically but created by traversing a hypergraph path. This allows a structured aggregation of permissions on resources. Consequently, multiple resources can share parts of their queries.


Niemann R.,Hof University of Applied Sciences
Proceedings - 2015 IEEE 10th International Conference on Global Software Engineering Workshops, ICGSEW 2015 | Year: 2015

In the last couple of years it became more difficult for end users of data management system to optimize existing systems for performance and energy consumption. The reasons are the big number of data management systems to chose from, extensive use cases and a variety of hardware configurations. The number of factors that influence the performance and energy efficiency rises even more when it comes to distributed data management systems. For instance, in addition to vertical scale-out effects the horizontal scale-out ones have to be considered. This paper introduces an enhanced version of a Queued Petri Nets model whose simulation runs allow to predict and to study the performance and energy consumption of a distributed data management system. In contrast to traditional ways, the simulation runs can reduce both investments in time and hardware. The model's prediction in terms of performance and energy consumption were evaluated and compared with the actual experimental results. The predicted and experimental results for the response times differ by nearly 20 percent on average. © 2015 IEEE.


Ignat V.,Hof University of Applied Sciences
IOP Conference Series: Materials Science and Engineering | Year: 2016

Advanced industrial countries are affected by technology theft. German industry annually loses more than 50 billion euros. The main causes are industrial espionage and fraudulent copying patents and industrial products. Many Asian countries are profiteering saving up to 65% of production costs. Most affected are small medium enterprises, who do not have sufficient economic power to assert themselves against some powerful countries. International organizations, such as Interpol and World Customs Organization - WCO - work together to combat international economic crime. Several methods of protection can be achieved by registering patents or specific technical methods for recognition of product originality. They have developed more suitable protection, like Hologram, magnetic stripe, barcode, CE marking, digital watermarks, DNA or Nano-technologies, security labels, radio frequency identification, micro color codes, matrix code, cryptographic encodings. The automotive industry has developed the method "Manufactures against Product Piracy". A sticker on the package features original products and it uses a Data Matrix verifiable barcode. The code can be recorded with a smartphone camera. The smartphone is connected via Internet to a database, where the identification numbers of the original parts are stored. © Published under licence by IOP Publishing Ltd.


Ignat V.,Hof University of Applied Sciences
IOP Conference Series: Materials Science and Engineering | Year: 2016

The number of patents is not so important as the market value. The market value is especially important for licensing of patents, make-or-buy decisions for technology procurement, corporate finance. Patents can be used as collateral for financing. Patents and credit approvals: without patents only 46% and with patents 54%. The value share of knowledge-based components to industrial products already reached 50% and it is still rising. OECD called these developments under the slogan "knowledge economy". German Norm-DIN 77100 provides a working method for monetary evaluation of a patent. The value of a patent arises from its use. A patent can be used to protect or to earn licensing revenues. An evaluation expertise is required in areas, such as marketing, finance, R & D and strategic planning. As an indicator of the value of a patent is often used the number of citations. The number of a patent citation refers to its meaning and value. Other indicators would be: size of the patent family, validity of the patent, result of objections against patent application, number and quality of claims. The analysis of 9.000 patents resulted that only 7.2% worth over 10 million euro and 68% below 1 million euro. The cost method: it is considered the cost that would be incurred for the development and patenting of a similar invention. The market method: are used the prices that have been achieved in comparable with recently transactions. The Income method: the potential reward is measured, which can arise from a patent. The evaluation will be in the following areas: legal status, technology, market conditions, finance and strategy. Each question relates to a different parameter of a value. © Published under licence by IOP Publishing Ltd.


Kropf C.,Hof University of Applied Sciences
DATA 2014 - Proceedings of 3rd International Conference on Data Management Technologies and Applications | Year: 2014

This paper presents the optimization of the reorganisation algorithms of hybrid index structures supporting multimedia search conditions. Multimedia in this case refers to, on the one hand, the support of high dimensional feature spaces and, on the other, the mix of data of multiple types. We will use an approach which may typically be found in geographic information retrieval (GIR) systems combined of two-dimensional geographical points in combination with textual data. Yet, the dimensions of the points may be arbitrarily set. Currently, most of these access methods implemented for the use in database centric application domains are validated regarding their retrieval efficiency in simulation based environments. Most of the structures and experiments only use synthetic validation in an artificial setup. Additionally, the focus of these tests is to validate the retrieval efficiency. We implemented such an indexing method in a realistic database management system and noticed an unacceptable runtime behaviour of reorganisation algorithms. Hence, a structured and iterative optimization procedure is set up to make hybrid index structures suitable for the use in real world application scenarios. The final outcome is a set of algorithms providing efficient approaches for reorganisations of access methods for hybrid data spaces.

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